Mac Mini Setup, Phase 2

Over in my other blog, Brick Pool House, I described setting up my new Mac Mini starting on Black Friday.  It went smoothly.  But I did not hook it up to my video system because I needed an appropriate Mini DisplayPort adapter(s).

One reason I had not bought a Mini earlier, say 2-3 years ago, was because I was worried about connecting to my video system as easily as I had the PowerBook which had S-Video output.

On Wednesday and Thursday I bought various parts at Radio Shack and Best Buy.

On Thursday night I hooked up a MiniDisplayPort to HDMI adapter "cable" from Belkin, which I bought at Best Buy.  What Belkin has done is package a short cabled adapter with a 7 foot HDMI cable for $44.  You could buy the separate parts but they would end up costing more.  Plus I figured these pieces were made to go together (they are, and the inline HDMI connection fits snugly).  I only worried that the actual "converter" circuitry might not be as good as the more expensive separate options.  But I figured it was probably about the same, and this looked neat.

Well at first I plugged in the display port adapter and plugged the HDMI into my 5 way HDMI switch (which feeds a HDMI splitter which goes to TV's in 3 different rooms) it did not work.  I fiddled with it on Thursday night for more than an hour and could not get it working.  I unplugged and replugged the HDMI cable.  I turned off the kitchen TV (an older model which has 1080i, but not 1080p) and tried the Bedroom TV (a Samsung from 2008) instead.  I rebooted the Mac.  Frustratingly, the Display Preferences showed only one device, the DVI monitor, and not anything else.   However, the status light on the HDMI switch did light up.  I changed the refresh rate for the (only one shown) display to 60Hz.  I also tried changing the display preferences down to 1024x768 (very similar to 720p) and even 640x480.

I did not re-plug the Mini DisplayPort plug itself, because that was tricky.  By the end of the night, I had removed the Mini DisplayPort plug, but been unable to plug it in in the dim light, and beginning to wonder if the Thunderbolt indication meant this wasn't really a Mini DisplayPort.

All night long I was dreading the possibility that this newfangled DisplayPort thing would not work a video switch.  Apple does indeed say you should not plug any other adapters into a Mini DisplayPort adapter.  They say you should ONLY plug an approved monitor into the adapter.  This would go way beyond the normal HDCP copy restriction if you couldn't even use HDMI switches and splitters.  But maybe that's what I was not stuck with.  Perhaps I could get the old PowerBook going again with a new Hard Drive.  This was the kind of thing I was thinking, and dreading.

In the morning I checked online, and in fact the Thunderbolt plug can work like a Mini DisplayPort plug if a Mini DisplayPort adapter is plugged into it.  Looking at one set of troubleshooting instructions from Mac, I noticed that as their last step, they had you remove and reinsert the Mini DisplayPort plug after shutdown and then restart.  The instructions were a bit ambiguous as if to suggest you should try re-inserting the plug several times even.

This time I was able to re-insert the plug, and it still didn't work right off, but after a bit more fiddling, it started working, and I got good images on both kitchen and bedroom TV's at once.  The second monitor now does show up in Display Preferences and I adjusted them for side-by-side.  I set the main monitor for "best display."  For some reason, the video system only gets 640x480.  I can only choose that.  I shut off the kitchen TV again, and on my Bedroom TV I could select either 640x480 or PAL, but no HDTV like 1080p.

It must be that my switch and splitter are sending some kind of least-common-denominator display information back up the line.  All of my TV's are capable of 720p and 1080i, but my Kitchen TV only does 1080i and not 1080p.  Perhaps the DisplayPort can't do 1080i (update: I now know that it can do 1080i from the adjustments with the Monoprice DisplayPort->Component adapter) and can't do 720p either but only 480p or 1080p.  That seems very limited, but it would explain what I am now seeing.  I have turned off the kitchen TV but maybe I need to disconnect it from the HDMI splitter to get a higher resolution.  Anyway, I'm actually glad it does support 480p, which is more appropriate for some things.  But what I'd like to do is be able to switch among these resolutions (and even 1080i, if that is possible, to get best image on my kitchen TV).

More fun with Kenwood L-1000T

Just a few weeks ago I hooked up my Kenwood L-1000T (aka Kenwood in this post) to my whole house Sonos audio system using a Behringer DEQ 2496 digital equalizer to correct the European 50uS deemphasis to the USA 75uS standard.  In the digital domain I can do the conversion quite well, even with the limited choice of cutoff frequencies.  I use a 6dB per octave shelving at 2212Hz.  Right now I can't remember the dB of adjustment but I think it was between 2 and 3dB (calculated in an earlier post).

Well of course I couldn't even enjoy the Kenwood over Sonos without this change (or something having a similar effect, like actually changing the parts in the Kenwood), so even though I had hooked up the Kenwood to Sonos back in July, I hadn't really used it much for the Kenwood.

What I mostly use this for is listening to radio in the bedroom.  The bedroom currently does not have any tuners hooked up (though, ironically, I have the stack of second best tuners that the Kenwood defeated now resting in the bedroom because the computer room has been overstuffed with junk).

When I used the Sonos system to listen to FM, which wasn't that often, I usually listened to the Marantz 2130 in the kitchen as it has the correct EQ and actually sounds very nice.  Sonos lets me pipe a line-input signal from any room to any other room, it goes through a moderate quality 44.1Khz 16 bit uncompressed codec with digital level adjustment so you can optimize the dynamic range.

This was a revelation.  The Kenwood always sounded great, but now I could actually stand listening to it for hours, and using my KT-6040 remote control, I spent one evening scanning radio stations.

On Tuesday night I found how the Kenwood L-1000T with correct EQ really blows away the Marantz 2130 over Sonos.  The Marantz sounds veiled and muddy by comparison.  (It doesn't sound that way at all in the kitchen, possibly because of different room acoustics and near field listening, but also possibly this test is unfair, I have fully optimized the Sonos level for the Kenwood a few days ago, currently max tuner output gets to -3dB digital maximum, but the Marantz level in the Kitchen has not been optimized, and was about 20dB lower, causing huge loss of digital resolution (though I raised the volume level to compensate, it can't restore the resolution lost over 16bit depth conversion and transmission).  Possibly the Marantz level actually depends on the volume level I set on the amplifier in the kitchen, actually a Yahama receiver.

But I also came to notice on Tuesday night this week that the signal from San Antonio City College was mono.  I noticed this because I happened to pipe the Kenwood output to the kitchen system, and look at the stereo separation on the L-R scope mode of the Marantz.

So I took a careful look at the display of the Kenwood tuner.  It was showing only one (tiny) bar of signal strength, yet the RF selection was Direct.  Obviously this was causing a weak signal and limiting stereo separation.

For some time now, I had been convinced that the 6040 remote doesn't control the station control settings on the Kenwood.  But somehow I had pre-programmed Preset 2 for Direct mode.  Either I had actually set the Direct mode somehow, or at some earlier time the signal strength may have been stronger when I was setting the presets.

I was able to un-set the Direct mode by this procedure:

a) Disable setup mode using small button to the right of tuning knob.
b) Change the tuning by the minimum amount in either direction.
c) Change the tuning back to the correct center tune.

This forces the Kenwood to determine the best settings for this station, and when I do this now, it correctly choses High Sensitivity mode.

Now the fact that the presets had been programmed with direct mode suggests that possibly I had been able to control the RF mode previously, and I had deliberately chosen direct thinking it would give the best sound quality.  Or, more likely, I had set direct mode for KPAC, a much stronger station, and had failed to unset it for the remaining stations that I programmed.

Taking the remote in hand again, I struggled and with much fiddling with angle and direction was able to get the Kenwood to change RF mode once.  I think the capability is actually there, I just lost it when I stuffed the Kenwood into the corner it now occupies, which gives no good way to aim the remote at it (the Kenwood is immediately behind the transformer of my Acoustat speaker).  I can try to control it from the side that I have open and it sometimes works.  I can also use the Remote Extender system which I use to control the preset station selection from the bedroom.  That also has a receiver over the living room mantel so I can point the remote at that rather than at the tuner.  It works, mostly, for setting presets, but may not have enough IR resolution for the advanced settings like the RF mode.  The remote extender has a transmitter I place just to the side of the L-1000T and it works, at least it works well enough to change presets.

It may also be the batteries in the 6040 remote have gotten weak.

I need to experiment with this more, it was already well past my bedtime when I made the above discoveries, and I decided to stop because I know these kinds of explorations can last all night and typically end on some frustrating note.  But I will be back at it soon.

In the meantime, I used my mis-tuning method to get the Kenwood back to receiving the city college station in High Sensitivity mode.  But if I change the preset, this gets messed up, so I really have to find some way to fix it.  I could also memorize the preset with the High Sensitivity mode.  But I also forgot how to program presets, I alway find this confusing and counter-intuitive on Kenwood digital tuners and I need to read the instructions again.

But another flaw is that I can't, or at least was unable, set the IF bandwidth.  When I change the RF mode back to High Sensitivity using the method above, it also resets the IF bandwidth to Narrow.  It really doesn't need to do that I think, as Wide works fine on Direct mode, it should also work OK on Narrow.  But as yet I haven't figured out a way to change that.  Perhaps the remote will do this, and perhaps it won't.

Here's a discussion of HDMI/HDCP handshaking.

There are endless blogs of people describing issues and frustrations with Apple's Mini DisplayPort.  Many people have suffered with the disappointment that they cannot use their cherished display with their cherished Mac.  And for many of those people, the problem did not go away the next day.

After you look at the discussion of HDMI/HDCP handshaking, it's not surprising that this technology is so finnicky.  HDMI/HDCP want to make sure you're not doing anything that isn't allowed (recording!).  And it seems, even a slight seeming irregularity will shut them down.  Also, all HDMI/HDCP units have an internal state, which may need to be reset by powering down the unit for 10 seconds.  You try powering down everything, making all the connections, then powering up switches, then displays, then sources.  If that doesn't work, try powering down everything and then powering up switches, sources, and displays.  Some configurations work better with powering source first, others with powering display first.

Oh Boy.

Playing with the Kurzweil

A month or so ago I pulled out my mint (barely used) Kurzweil K2661.  Over in the corner where it has had a nice custom made table to sit on for the last 4 years, it has mostly just sat, because it's just no fun to stand in that corner and play.  So I pulled it out right in front of the Queen Anne chair at the back of the living room.  That makes for a great place to play.  It is lined up with the L-R of the speakers.  Obviously one does not get the incredible image one gets up front.  But one does get a nice distant image that I find good enough, and the back of the room, and the Queen Anne chair, is much more suited to playing than in front.  And the beauty of this arrangement, with playing chair in the back and listening chair up front, is that both are independent and always available to be their best.  I can leave the Kurzweil out for the whole month until my end-of-the-month party, when I can temporarily put it back on the custom made table in the corner.  The rest of the time, it can be out in the room.

That's exactly what I did for the party in October, I put the Kurzweil away on the morning of the party and back after the party, so it was unavailable for the minimum time.  And when I set it up this time, I skipped all the wiring mistakes I made the first time, and got the wires entirely out-of-the-way instead of taking-up-the-whole-room.  There is one passage, around to the couch in back, that has become a bit tricky mainly because of the Kurzweil itself.  But now I make the front path to the couch around the listening chair entirely clear of wires.

Since I purchased the music workstation in 2006, I suspect I've used it less than 400 hours, mostly just random playing, barely learning how to program or do anything (though I know it's all there...it can do anything, well almost, play all parts you've recorded at once, just like a full band, with accurate (to varying degrees) renditions of every kind of instrument or synthesizer, and every aspect of every Program (instrument) can be edited, or new ones can be created from factory samples or new loaded samples.  The Kurzweil gives you a nice collection of samples and raw sounds and an all-inclusive (just about) set of all the possible transforming operations that could be done with them, and then you can hookup as many of one to the other and to controllers in as many ways you can imagine in fairly long channels.  Thus, it makes you the instrument designer, and you can make it do anything anyhow.  It's a kind of soft instrument made of user programmable DSPs, which uses actual DSP hardware to realize how it is programmed.  A true analog instrument with as many capabilities as this would fill a building.  (DSP = Digital Signal Processors)

Last month I finally figured out Record Mode, or at least I recorded myself a few times, and it actually worked.  I've been watching the video tutorial that I downloaded from Kurzweil or somewhere when I bought my unit.  It's good, but it doesn't start with creating Programs and so even though I've now watched half of it I still haven't gotten to the programming part.  I watched him record a sequence, and after that I got it to work.

Here is one of the better tutorials I've seen on creating a Kurzweil Program.

http://kurzweil.com/knowledgebase/k2600r/program_mode/88/

Two Steps Forwards, One Backwards

After getting back home from a long Saturday (trip to nursury, dinner, concert) I thought I'd catch up on a few audio issues in the master bedroom.

Ever since I set up the Linn Sondek turntable system a few months back, I haven't had a 24 bit ADC to digitize the output of my Denon 3910 DVD-Audio/SACD player.  I moved the Behringer DEQ 2496 over next to the turntable to keep the analog lines short.  So I had to plug the 3910 straight into the Tact RCS 2.0 analog inputs, which are notoriously 16 bit (or at least 16 bit performance).  To add insult to injury, I also had to attenuate the DVD player output with a 6dB attenuator to be sure it did not overload the maximum 1.5V input of the Tact.  Actually, 3dB would have been sufficient, but when I set this up I had run out of 3dB attenuators.

To fix this, a few weeks back I have moved the MSB PAD-1 into the bedroom, but hadn't hooked it up.

Here's a list of things I ended up doing:


1) Removed Acurus L-10 preamp, now possibly not working (or at least LED not lighted).

2) Removed Yahama T-85 from underneath Tact.  The T-85 has issues and I haven't used it in several years.  It was finally convenient to remove the T-85 after I removed all the stuff on top of the Tact.

3) Vacuumed, vacuumed, vacuumed (top of Tact, MSB, Aragon and rack)

4) Hooked up the MSB, including its power adapter, and hook its AES/EBU output to the Tact (#5).

3) Moved the Aragon 28K preamp on top of the MSB.  It had been over near the phonograph system, but was not being used.  I had tried using it instead of the tube preamp for the Panasonic strain gauge cartridges, but it didn't work well in that application, nevertheless it had stayed there.

4) Hooked up the 28K to the analog output of the Denon.  Only the Denon is now hooked up.

5) Removed old analog line from TV to Acurus.  Apparently I had set up this line because the digital link from TV to Tact was once not working well.  I figured out why also (see below) and fixed it.  This line used a long interconnect, two 3dB adapters, and a Radio Shack isolation transformer.

6) Moved 30 foot Toslink connection from TV to Behringer used for phono system.

7) Extracted M-Audio CO2 from living room and connected to Tact with coax (finally using fancy radio shack coax, one from BJC was too stiff).  This adapter converts toslink to coax digital so I can use one of the 3 coax digital inputs on the Tact.

8) Tried BJC toslink from TV to CO2.  Very intermittent, usually not working unless I wiggled the cable at the input to CO2.  Now I remembered I had this problem before.

9) Extracted a 2nd 30ft toslink cable from behind the sofa in living room.  That second cable has been ambushed there by a snarl for several years.  Using that cable, the CO2 worked fine, so now the digital connection between TV and audio system works fine, and also allows remote switching to the digital connection between phonograph and audio system.  Previously I had to manually switch the one working 30 foot toslink cable I had between TV and phono system, which didn't encourage me to play more records.

10) Adjusted gain on 28K so that Denon would not clip MSB.  My first test was playing a Chesky jazz disc 'Havana' over and over and noting the peak level.  That was a very time consuming test, but the disc was already in the player.  Later I used the Stereophile test disc 2 on track 17 and noted the "average level".  Finally I used the 19+20K distortion test, turning off the DCX so as not to play through speakers.  With that test playing at 0dB, I had average level about -3.5dB with volume control at about 2:30.  Peak level was just above -20dB, but I don't think that is a problem.  I need to make a better test disc for this purpose.

11) Finding that I couldn't see the Denon on my TV, I reconnected the S-Video cable that goes through Isomax transformer.

12) I played a multichannel SACD and was finding that despite setting SACD control to stereo, the indicator still showed multichannel output.

13) Fiddling with the Denon setup menu, I found it was necessary to turn the Denon-link off in order to adjust the audio from multichannel to stereo.

14) I listened to several discs, notably Hanson conducts Hanson, as background music as I was working on stuff.

15) Once I got the TV working over the 2nd toslink cable, I ran that for several hours to make sure it was working without cutouts.  It was playing a Nova special on string theory.

16) Tested phono system which I haven't used for a couple months.  The Linn appears not to start.  The pushbutton light goes out quickly after the start button is pressed.

****  So I went to a lot of work to make it possible to switch digital inputs from TV to Turntable and back, and then guess what, the turntable stops working !!!

I may fiddle with the Linn a bit more.  Also this might be a good time to check out the Sony turntable.  I never actually inspected the Sony circuitry, I just disconnected it at the first sight of bad operation.

It's sad that my phono system isn't working again.  But it seems I like to play DVD-Audio and SACD discs more anyway.

Ground loop hum from HDMI even over CAT6

One reason I had been using a fiber optic connection between kitchen and living room was electrical isolation.  The fiber optic connection could not in any way create a ground loop.   I decided not to use another fiber optic system because it would have cost a minimum of $300 more than the CAT6 alternative, and possibly much more, and because the CAT6 connections are cheap enough I could extend them to even more rooms.

I was hoping that the CAT6 digital video balun, which transforms the HDMI transmission into one that goes over a pair of CAT-6 wires, and then back to HDMI, would not induce the ground loop, given that the two baluns would isolate the ground.

Unfortunately, it did not work that way.  Once I hooked up the new video connection system using CAT6 and baluns, I did get a slight amount of ground loop hum in the living room system, regardless of analog input chosen.  When I disconnected the RCA's from the TV, or disconnected the HDMI cable from the TV, it would go away.

So I went through my cable box and could not find any more Jensen Isomax CI2RR audio isolation transformers with RCA jacks.  I did have one spare unit last year, but I took it for the computer I use at work, which creates horrible hum because the computer is plugged into an online UPS but the amplifer isn't.  I had been using a cheap Radio Shack isolation transformer there, but apparently the current running through this ground circuit when the UPS is power the computer was great enough to burn out the Radio Shack unit.  So far the Jensen has not suffered the same fate.

So for the last week I had been using a spare Radio Shack isolation transformer.  It did the isolation job fine, though I wondered if it had the best audio fidelity.  (From measurements, I know it gets rather high bass distortion if level are high enough.  The Jensen is almost perfect, as it should be for about 10x the price of the Radio Shack unit.

So today I have ordered another CI2RR isolation transformer, along with an 18 inch DVI cable (for the HDMI audio inserter I use on my harddrive recorder which has no HDMI outputs), and a VS-1SS S-video isolation transformer I can use with the Denon 5900 in the living room I use for audio discs.  The living room TV has only one HDMI input, so normally it will be connected to my kitchen video hub.  On special occasions, I could hook the Denon to the TV using a DVI/HDMI connection, but it's not necessary normally because I can use the Oppo BDP-95 in the kitchen to watch video discs instead, and that will always run through the new CAT6 HDMI connection.  Full remote control of the Oppo works great too, through the Radio Shack Remote Wireless Extender transmitter I have in the living room.

Fun with FM and TV

I have been finding that my Kitchen system has more clarity on FM when playing in the "Direct Stereo" mode of my Yamaha receiver.  That mode bypasses analog-to-digital conversion, DSP processing for eq and crossover and surround, and digital-to-analog conversion.  I know that the Direct Stereo mode bypasses all this because I tested it many years ago.  It's quite clear when digital processing is being done, because square waves coming through the unit have that distinctive pre and post ringing at ultrasonic frequencies.

Well usually Direct Stereo sounds better, and I think it's mainly because of the crude crossover that is being used, that crosses over to subwoofer at 100Hz or 80Hz, most likely at 12db/octave.  In the bedroom, a larger room, I cross over the subwoofer at 48dB/octave at 60hz.

I had usually kept the receiver on "2 channel stereo" because, despite the name, that is the mode that uses DSP to implement the crossover for the subwoofer.  That still works best if the deep bass is the most important part of the sound.

*****

I've also tried some surround options.  Concert Hall uses DSP processing to get a concert hall effect out of 5 (or 7) speakers playing plus subwoofer.  It makes the normal stereo seem a bit wider.  It has the most impressive effect on a mono announcer, he sounds like he is speaking from the stage in a big concert hall (duh).

*****

Over the second weekend in May I finally got my living room TV hooked up again to my central video system (in Kitchen).  That means I watch satellite TV and hard drive recordings and and computer and DVD's and even Blu Ray discs from the living room TV.  That was what I had set up in mid 2009, but late in 2011 the OWLink optical transmitter for HDMI to the bedroom failed.  I replaced that transmitter with the one that had previously been used for the living room, and ever since then, there has been no video system connectivity to the living room.  (The bedroom is the most important video link, I use that connection daily.)  For showing my monthly movies in the living room, I've typically used the Denon 5900 player there, and fortunately all the movies I've shown since November have been brand new (no concern about dirt from rental movies).

As discussed in this blog, I investigated several options.  I could buy a new OWLink kit for about $450.  They are very very hard to find (out of production for several years) but can be found.  There were other optical options as low as $299.

I decided to try a CAT6 balun instead.  They are much more widely available and more reasonably priced, from many brands, and the connecting CAT6 wire is a commodity product which can be readily replaced or extended.  I got the basic kind that uses two CAT6 wires.  This has essentially the same number of wires as the HDMI cable itself, so the system is relatively low cost.  Much more expensive systems manage to cram all the information into a single CAT6.

Setup was actually quite easy.  The hardest part was running the two CAT6 wires, but even that was fairly quick.  I had bought the 50' CAT6 wires from two different Best Buy stores, but they worked fine together.  I also hooked everything up to make sure it worked before running the CAT6 cables behind the couch and under the kitchen counters.  That pre-testing made running the cables harder because the cable became a huge snarl rather than a small roll that could be simply unrolled.

Another trick was getting rid of the audio hum.  After the HDMI through balun from the kitchen was connected to the living room TV, the audio output goes into Analog 1 of the TACT preamp.  There was a bad hum after hooking up the HDMI because of ground difference in the two powerline circuits.  So I used a Radio Shack isolation transformer on the audio line, and it fixed the problem.  (Now if I could only get KPAC to fix their hum problem.)  I plan to replace the Radio Shack isolator with one from Jensen that I use in other locations.  The Jensen transformers are very good, but also this is only TV.  If this were a high resolution audio line, I'd figure out some other solution.  The main other solution would be going back to fiber optic  HDMI.  I was hoping I wouldn't have to do that, and it has turned out that I don't need to, but I did need to use an isolation transformer.

I also took the opportunity to add the DVI-plus-Audio--to--HDMI adapter to the DVI line from the Anchor Bay DVDO.  That means the audio signal is sent down the HDMI connections to living room and bedroom from the hard drive recorder.  I had been using that for several months now, but it got taken off during the massive rewiring on the previous weekend that moved DVDO and HDMI-switch into the main rack for reliable remote control from all rooms.

I also replaced the 15' HDMI cable (borrowed from the Mac-to-Bedroom-TV connection) with a new 12' HDMI from Blue Jeans cable.  That means I got the Mac-to-Bedroom-TV cable back, for use in the bedroom as intended.

The system currently lacks a "rental" dvd player because that unit, a Denon 2910, is still under the table where there is no no remote control (I've given up trying to get remote down there through wireless transmission, that was the whole point of the rearrangement) and no HDMI connection to the main switch.  Probably that player should be moved to the main rack also, so it can be controlled by remote.

Resolution needs more bits

Resolution is not "signal to noise ratio (SNR)."  Resolution refers to something we can't easily measure directly, but infer, in analog systems.  Analog amplifiers have the potential ability to reproduce every voltage level from zero to maximum, subject to limitations (noise, distortion, etc) which are additive in nature.  If the world were truly continuous, this would mean it can reproduce an infinite number of potential voltage levels, for in between each two levels we could specify, there would be another.

It is already known that we can hear a signal even when embedded in noise that is equally loud, so long as there is some other characteristic we can use to distinguish the signal from the noise, such as frequency response.  If the noise were pure gaussian, and the signal a pure tone, it is easy to see how this could also be done electronically as well as by ear.  I can't think of a general rule which would describe the limits of ability to do this.  For quite some time, it has been claimed that we can still hear the signal even if the noise is 15dB louder, but if our hearing were as good as possible for any acoustic sensor, and we had some pre-knowledge of either the signal or the noise, the noise could be much higher still relative to the signal.

Digital audio systems have been designed to have SNR nearly as good as the best possible analog equipment, and far better than most, with the potential 96dB SNR at 16 bits.  Perfectionists like me have sought to use 24 bit digital audio systems that have potential 144dB SNR, which is better than the best available analog amplifiers.  That has to be good enough, right?

Well, no, if the goal is to have the same resolution as analog systems.  I can't prove that we need this extra resolution, but I have some suspicions that it is, and I think it's interesting to think about what that kind of performance would require.

The answer seems to be we need bits to encode resolution down to some appropriate quantuum level.  Assuming the world is like that described by quantuum mechanics, 

quessing an appropriate quantuum level to be about 10^-33 volt, the number of bits required for 0-1V would be about 76 (2.3 bits per decimal digit x 33).

I can imagine a 24 bit encoder expanded to full 76 bit capacity.  Alternatively, and even given off-the-shelf parts, one could cascade multiple 24 bit encoders.  Suppose a successive approximation method is used, then we could simply make sure that 76 iterations of successive approximation are done.  Now we can't prove we have 76 bit accuracy, but I wasn't so much worried about accuracy as resolution.

Now such a digital encoder would probably not perform as well as an ordinary 24 bit one with regards to signal to noise ratio.  But often analog systems don't do that either.

I say not to worry about either the fact that SNR is not improving or even getting slightly worse.

Now I've only been considering the quantization accuracy here.  What if we consider time, making the sampling interval as small as possible.  Well, that gets us into trouble very quickly.  It is clear we have no hope of digitally encoding at something like a quantuum rate (10^-30 sec), and we would have no hope of storing so much data either.

My guess is that, for us, the amplitude accuracy is more important than the timing.  I've generally felt that 96Khz sampling rate is sufficient.  For what it's worth, audio research published in JAES has claimed that jitter, for example, isn't audible until we get to the 100's of nanoseconds, about 1000 times worse than the level modern digital equipment performs at. 

A 76bit/96Khz stereo datastream would require less than twice as much as a currently used 24bit/192Khz datastream.  It would be quite feasible to implement, if you were making digital converters anyway.  A major problem would be fighting off the nags who say it isn't necessary and has no proveable benefit.