Cullen ZP-80 Mod and D-Link 3 mod

I finally took the time to plug in one of my non modded sonos zp80's next to my cullen modded zp-80. I then tried to A/B. It was not blind and I had to swap the coax cable that runs to my benchmark DAC but I could tell a differnce (I thought).
My next step is to enlist the wife to make it blind...

I just had Rick Cullen do the ZP 90 mod and install a cardas AES/EBU cable
running into a Wadia 521 dac with GNS reference mod and I am thrilled.

I really agree with Frederick21's response. The digital volume control on the Sonos (or any nearly any digital volume control) loses resolution at low volume levels. You might not listen for these details as much during low volume levels but this is where most of us spend the most time enjoying music. For my main system, I am going with a preamp (The Supratek Chardonay) to maintain the music and full sound at low volume levels. This means the Sonos volume control will not work (it will be fixed). For my other systems in the house, I am just going with the digial volume of the Sonos for convenience sake.

A concern I had when deciding on a DAC to add to my Sonos system was if it had a volume control (like the Benchmark). You want the Sonos to be near the max volume setting to send the most accurate digital bits to your DAC. Thus, the DACs volume control regulates how I can best attain near max volume for the loudness I generally listen to music. This allows you to use the convenience of the Sonos controller. Loss in sound quality happens at the lower/lowest listening levels of the volume bar from Sonos. If the DAC can't 'regulate' the volume you might be listening to levels predominantly at the low end of the Sonos controller and thus are sending digital bits to your DAC that aren't as 'bit perfect'. So beware of what DAC you use and how you use it.

Thanks for the write up on the zp80 mod. I just added the benchmark dac1 to my system in hope of improving the zp80 experience.
Are you able to A/B with a non-modded ZP80? Just curious how much of the improvement comes from the great dac that you added and how much comes from the zp80 mod.
THX!