For those that have separate Streamers & DACS

@lordmelton  Your setup is an example of topic I raised above, You prefer your 005 with I2S vs usb, and for exactly the reasons I stated. While your Aurrender does have somewhat upgraded/optimized usb, it is not 100% galvanically isolated, does not run off dedicated lps (I may be wrong here, believe you mentioned it does have separate transformer, this with switching power supply?) , and the usb board itself does not contain a dedicated power supply (this would supply filtering,perhaps voltage regulation), I"m not even sure of the quality of the clock on that usb board. the best rendering streamers and/or server/streamers do all this. Its not hard for me to believe you prefer I2S vs usb with 005 while I prefer usb with my superior usb rendering via OpticalRendu (which has every optimization mentioned above) with 005.

And this is with an Aurrender model with superior usb rendering vs most of what I see in server/streamers.

The iFi Zen was a little kludgey for initial setup but it sounds far better than I expected. At a $399 price point I wasn’t expecting much and I’m still pleasantly surprised.

The Zen stream was an interim purchase for me as my previous streamer had died and I needed something quick. I assumed I’d be trading up within a few months of finding my next streamer.

Maybe not though. I’m still really enjoying the heck out of the iFi zen. And I’ve got a Matrix Audio X-SPDIF 2 on the way to serve as an I2S converter between the USB iFi Zen and the I2S interface on the DAC.

put a decent 12v lps into the zs and it takes another meaningful step up in sq - for the $ just crazy crazy good... people over-use the term ’giant killer’ but i think it can apply here... or at least ’giant-matcher’...

note: my use is in roon-mode, with cleansed ethernet feed into the z-s, with sotm 12v lps - i won't purport to say it beats much more expensive ones in other modes

@sns I have a double tailed USB cable with the power pin taped over at both ends, so the signal side is not influenced by any RFI/EMI.

However the 5vdc power side ground is still connected. I have tested with and without 5vdc ground but ground sounds better.

My USB to I2s DDC is powered by a quality LPS, no power from USB.

I2s RJ45 cable into my Musetec 005.

The sound is superb but the USB and I2s cables are high quality.

I have thought about optical isolation but honestly the sound I'm getting is wonderful.

Appreciate all of the responses and opinions.  I agree that the DAC choice will have a big impact on the final choice of streamer, and also know that not too many folks actually build their own streamers.

Some things I have personally had in my system for sometime and kind of how this got started for me.  In my second system I had a Bluesound Node 2i going into a Chord Qutest.  I replaced the Bluesound with the iFi Zen Stream and noticed a surprising improvement.  Over time, I've upgraded my second system so that it now rivals my main rig and the last piece of the puzzle is the digital source and DAC.  I moved the Innuos Zenith MKIII into the system two to audition DACs and noticed how much better it was than the Zen Stream which started me wondering what would be the ultimate best fit for my final DAC choice.  Right now, the leader in the clubhouse DAC wise is the Merason DAC1.  I've also lining up a Bricasti M3 audition and an Ideon Ayazi audition for DACS and have already played with a few others.  Based on my system, I've eliminated anything Chord and Weiss.

Assuming I decide to spring for the Merason, some streaming options that I'm thinking about include the newer Innuos Pulse series, the Bricasti M5, the Auralic Aries G1 (not sure what the bump to 2.1 would get me), something from Sonore and maybe something from Aurender (but the lack of Roon does give me pause). 

System is Fleetwood Deville's, Backert Labs Rhythm 1.3 and McGary SA1E.

Streaming dacs are also good way to go, less complexity,  greater assurance dac/rendering interface optimized.

@lordmelton Yes, while your usb is relatively good compared to many, yuur I2S has greater optimization, don't doubt your fine results. And yes, your partially optimized Aurrender usb would benefit from external usb renderer via any number of streamers, the OpticalRendu being but one.