A month ago, I purchased a new streamer as I was certain it was the weakest link in my system. I had previously been using a Sonos Connect modded by W4S.
The Sonos Connect allows you turn off its internal WiFi module if using ethernet. I found this gave a slight improvement in SQ - and confirmed to me the benefit of reducing electrical noise in your digital chain and components.
I use the Netgear Powerline devices to get ethernet to my streamer. Based on the status lights on those devices, I was linking at less than 50mb/s, and sometimes I would completely lose the ability to stream 16 bit FLAC files - dropouts, lost link, etc. That’s only, what, 1.4 mb/s? Very frustrating, but with the Connect, I could just switch back to streaming via wifi.
The digital chain is:
Router -> Powerline adaptor -> wall sockets -> Powerline adaptor -> streamer -> DAC (spdif)
My new streamer does not have WiFi. I had to solve the powerline dropouts, and I also wanted to reduce noise in the chain as much as possible to get the most out of my new streamer (which was immediately a major upgrade in SQ over the Sonos - even with my finicky and poor networking architecture).
I changed out my router from the Comcast router to a Motorola. My wifi performance improved, but the ethernet issues with the powerline adaptors did not. I then switched out the stock SMPS on the router with a Sbooster LPS, and replaced the unknown/stock ethernet cable with the Blue Jeans cat 6a. The powerline adaptors were now linking at 100mb/s with no dropouts and I heard improved sound.
Steve Nugent from Empirical Audio suggests "fast" LPS for routers, switches and streamers - anything digital. He stated the Sbooster was "fast", so I went with that one. I think this might be related to the power supply "pumping" injecting noise that @atdavid has brought up. I don’t know, but I do know this change helped.
I was reading about audio network switches as a upgrade (to be deployed between downstream powerline adaptor and new streamer). I was having thoughts similar to
@almarg in that, as he stated better than I could:
"differences in waveform characteristics in turn may, IMO, affect the degree to which some of the RF energy present in the signal may bypass, i.e., may find its way around, the ethernet interface circuitry in the receiving component and affect circuitry that is further downstream".
Knowing the powerline adaptors were probably noisy as heck, going the switch route seemed like it would be less effective than isolation. So, I decided to buy the
Gigafoil v4 ethernet filter - basically a ethernet-to-fiber-to-ethernet device that removes potential noise on ethernet cable.
I’ve powered the Gigafoil with an Sbooster LPS, and connected it to the network with a Blue Jeans cable on input side, and a higher end cable on the output to my streamer.
The results? I totally concur with @parsons previous comment: tighter and more realistic base, lower noise floor, relaxed, dynamic and I can listen to it out much louder volumes comfortably.
I have a power cable for the new streamer on the way, as well as a new coax cable. Hopefully, those will be that last upgrades for a while.
Sorry for the length of this. I wanted to share some recent experience related to this topic. I totally agree with
@grannyring :
Everything matters in our digital audio front ends. Everything folks.