Emotiva Stealth DC-1 updates

The "4th" DAC in my living room system had been pulled out for dead over a year ago.  An Emotiva Stealth DC-1, I was meaning to send it to Emotiva, etc.

I brought it out for testing a week ago on the bench, and it was not dead at all.  Working fine.  I hooked it up to the living room system and ran it for a week without issues.

May have been, much with the right subwoofer recently, the power cord had previously come detached.

Anyway, this was a good time to check the XLR cable interaction, firstly with this DAC (which actually was my original DC-1, which had 0.25dB adjustment which I prize) and the other I now normally have been using, and with the new custom cable I got from Cables For Less.

Sometime last year I had discovered to my horror that despite my constantly obsessing over low hum and always listening for it, my system had indeed developed (and probably had for several years, at least since I quite using the Krell) a very small about -60dB hum in both channels caused by a ground loop in the Emotiva Dac.  Even with AES XLR input, which is supposed to be fully transformer connected, a shield connecting in the cable is enough to create the ground loop.  This may be a construction or design error on the part of the Emotiva.

I possibly didn't matter when I was using the XLR outputs with my Krell amplifier, but when using the unbalanced output for most of my amplifiers, including my now daily used and beloved Hafler 9300, I don't have that option.  (BTW, IMO the 9300 design is superior to that of larger 9500 model with balanced inputs...despite the balanced inputs the distortion levels are about ten times higher.  With the Acoustat 2+2's one really doesn't need more power than what the 9300 can provide, and it has incredible peak power and amplitude as well, and incredible high frequency damping factor...it measured better than the Krell in that regards, and comparable in everything else except max power.)

I was not able to eliminate the hum by merely lifting the ground, but I was able to fix it by cutting the shield of my xlr cable.  (I can't remember if my hand made cable just cut the shield or also lifted ground.)

Well I happened to email cables for less because they said they would do "custom cables" so I asked for a custom cable with the shield disconnected.

Somehow I got into an argument with the principal by email but he assured me his cable would not cause a ground loop.

Well, sadly, it did, and he agreed to fix it.  But it took me months to get around to sending it back, and they demanded payment not for the modification but shipping.  When the newly modified custom cable came back, it simply sat on the pile for months, until yesterday.

So now I had the perfect opportunity to test both Emotiva Stealth DC-1 Dacs with a variety of cables, including the newly modified one to see if they finally got it right.

Both Stealth DC-1 dacs show the identical issue with AES input using standard AES cable, which ultimately results in 2mV hum and noise level (A weighted) measured at speaker terminals.  (Measurements last year showed the 9300 amplifier almost unbelievably quiet with shorted inputs, nearly all the noise was being produced by the DAC.)    My modified cable eliminates that problem, and the newly modified one from Cables for Less does also, as close as I can be sure of, to about 0.17mV, all measured by my Meguro meter.