Do Streamer only devices really impact sound quality?

I wonder how many people have compared I2S with USB in a well-controlled A/B test.  I2S still isn't all that widely available.  My streaming DAC does have an I2S input but I've never used it.  In my system, the most likely path into that IIS port would be from my Mac's, uh, USB port, via a converter box such as the Sonore ultraDigital or the Matrix X-SPDIF 2.  I've been slightly curious to see if that would produce a noticeable improvement, but don't really want to add another little converter box into an already cluttered system. Besides, the SQ already is pretty darn good.  But I do wish my music server (the SGC sonicTransporter) had an IIS output port. My DAC with IIS input can support 16-32 bit PCM, while its USB pipeline supports only 16-24 bit.  Perhaps more importantly, IIS might eliminate the annoying USB handshake problems I sometimes experience.

IIS from the Matrix X-SPDIF seems to be popular among users of the PS Audio Direct Stream DAC. I wonder if this popularity doesn't stem from limitations of PS Audio's USB implementations, or from problems with the Direct Stream's network bridge card. Point is, again, that if we're going to compare USB to IIS, I think we need to specify the context of how USB is being implemented in the system we're comparing.  

@tk21 You got it, context is everything.

@adasdad Not going to speak for ghdprentice, but my custom build streamer has been directly compared to top tier streamers such as his Aurender, Taiko Extreme, as well as to many lower tier, and it rightly belongs in that tier as both previous owners only sold after comparing and purchasing Taiko Extreme (and this prior to JCAT LPS I power it with).  The top echelon streamers pay extreme attention to noise reduction via top quality power supplies, jitter reduction via latency optimization and rendering via clocking and noise reduction of various ports. So, these are some of the theoretical reasons  for improved sound quality.  And then we have the listening portion, some may not consider that to be valid, but between what others report and what I've experienced with streamers, sound quality is extremely variable, at least on par with dacs. I can only say, try various steamers for yourself, assuming your system has sufficient resolving powers, the value of top tier streamers will be patently obvious.

I also have the ability to directly compare various protocols via drop in PCIe cards from Pink Faun and JCAT, top flight cards are available for network, coax, I2S, AES/EBU, USB. Presently using JCAT net XE to Sonore setup (FMC to USB), sound is simply sublime! I could stay here for the remainder of my life, never heard higher resolving, greater sense of ease with digital. Had to greatly upgrade my vinyl setup to keep up. Perhaps I'll compare other protocols over time, simply not motivated at the moment.

I'd only say believe those with top tier streamers, they are indeed hearing what they claim to be hearing, they are not delusional! I don't care about the damn theoreticals, audio is for our listening pleasure, not meant for some listening bot or textbook.

@sns 

I'd only say believe those with top tier streamers, they are indeed hearing what they claim to be hearing, they are not delusional! I don't care about the damn theoreticals, audio is for our listening pleasure, not meant for some listening bot or textbook.

indeed... nor for "measurements are everything" geeks

@adasdad

Very funny.

@dvdgreco When I started off on my recent complete overhaul of my hifi, I was similarly convinced that surely 1s and 0s are sacrosanct, and what is the point in buying better than a budget Cambridge streamer/DAC.

It wasn't until I tried several different USB cables between my new Zenith and Hegel H390 did I fully accept that such a thing as quality exists in the realm of digital signals.  Not only that, and this surprised me, USB cables to my ears have definite characteristics, which myself and other reviewers could agree on.  For example, the Laboga Emerald USB has a lovely warm and rich tone to it.  Why?  who knows - maybe not even the cable designer.  

In my experience, everything between the router/switch and the DAC's input affects the SQ to some extent.  Filters, regenerators, ethernet cables, USB cables, power supplies and, yes, the streamer.

Of course, the impact of each will depend on partnering equipment, and I would expect that some DACs are more sensitive to noise and jitter than others.  

Thankfully, most suppliers have a returns policy - though burn-in can be an issue, and eventually you'll just get tired and even a little neurotic by continually performing A-B comparisons and "staring" at the music, rather than just listening to it.

My advice: aim for a warmish sound, then stop and enjoy.  High levels of detail, in the short-term, is impressive, but can soon fatigue.