New Sonos in 2nd bedroom sounding great

Gallo speaker mounted in right upper corner of bedroom 

In the past week I've fixed two fundamental problems with Sonos in the 2nd bedroom.  First, I made it possible to get the ethernet connection from the Kitchen (which has a Dlink fast managed switch that now directly connects to all Sonos boxes in my house) instead of the Computer Room (where the old internet router creates a bottleneck for the whole network), by changing the HDMI over Cat6 video extender to a better model which only requires one Cat6 cable, leaving one of the Cat6a STP lines from Kitchen to 2nd bedroom available.  Then, I figured out how to fix the persistent ground loop without ground lifting the Parasound Zamp V.3 amplifier--by attaching the Sonos box with a short length of unshielded ethernet cable.  (Currently using an ethernet coupler at the end of the existing 10' Cat6a STP which attaches a 5 ft Cat5e UTP, the best short UTP I could find on hand; I have purchased online a 10' Cat6a UTP which will ultimately replace the 10' STP.)

On Tuesday I went even further and figured out how to get mono out of the Sonos box with two Harrison Labs attenuators and a Y adapter.  I also neatened up the cabling somewhat (though you might not see that from the picture) and tucked the bare metal shielded ethernet coupler (possibly having some inductive leakage, though I couldn't feel any) in between the gear so it would not be touched by dog or cat under the desk.

Zamp, Sonos, and outlet strip installed below small desk

It makes a huge difference to get the full L+R output rather than just Right Channel even though there is still only one speaker.  I've started working on mounting the Left speaker but it may not be fully hooked up for awhile because I'm planning to use "invisible" paintable flat cable.

I was enjoying listening to KPAC over the Sonos in this room, in true mono L+R, while simultaneously playing line inputs through all other Sonos boxes in the house.  Using the line-input feature in Sonos is the hardest test of Sonos networking, and in my experience, the most valuable usage of Sonos.  In one test, I was even playing the input from the master bedroom on the 2nd living room box, even though that box isn't hooked up to anything.  With all 5 boxes in line-input play on other boxes, I might have heard some glitching while I was brushing my teeth (so I couldn't be sure it wasn't the station having trouble at 5am).  When I rolled back to the 4 boxes I actually play from, there hasn't been any glitching in 3 days.  So the new network design using a fast switch in the Kitchen is now a proven success.

(When first setting up the 5 line-input test, the living room box hung and needed rebooting.  That box has needed a lot of rebooting over the last few years and possibly should be replaced for better health of the entire system.  Since the last reboot, however, everything has been running fine and glitch free for days using 4 boxes for playback of line inputs on other boxes--except that the living room box has only been used to play it's own line input.)