I chose to supply my own modem and router with my internet provider. I did place low noise power supplies on both the modem and router--I used iFi power supplies. I didn’t hear a difference when I placed them into the chain. However, I haven’t tried removing them from the chain, and sometimes I only hear a difference after removing something. Also, my total (retail) system cost was about 2k at the time I introduced iFi PSs to the modem and router, and now my total retail system value is about 5k. It’s possible that my system wasn’t resolving enough at the time to hear a difference, but that it might be now.
Like you, I’m looking for upstream solutions to improve sound quality. Here’s the short list of obvious audible upstream improvements I’ve had: DAC upgrade, streamer upgrade, reclocker/master clock, power cables/supplies for the DAC/streamer/reclocker.
I am currently flirting with upsampling, upgrading coax internet cabling to solid core copper coax, and converting the internet coax cable to optical right before the streamer. All of these projects are still TBD. I’m anticipating a nice improvement from converting to optical. My recommendation to you would be to look at optical conversion first, if you haven’t already. Your EtherRegen switch has an optical-in. You don’t necessarily have to run optical through your walls to start. You can start by just converting to optical right before the internet enters the EtherRegen. That way you can play with single-mode and multi-mode SFP transceivers and optical cable to see if one option sounds better than the other. You can also control for media converters (by EtherRegen or Sonore e.g.) and their power supplies. There may also be audio-grade SFP transceivers and optical internet cable I don’t know about.
