Do Streamer only devices really impact sound quality?

For many devices recently on the market, the streamer is integrated with a DAC and possibly preamp capabilities (volume control, source selection, or both). So chances are, you won't be hearing the "streamer itself" in isolation from one or more of those other functions. Furthermore, streamer A and streamer B may be delivering different combinations of software effects (DSP) or source content, which all color the output. FWIW, Stereophile does not have a separate category for "streamers" in its annual list of recommended components. They have a "digital processors" category, which mostly covers DACs (many of which have integrated streaming or preamp capabilities, equalization, DSP, etc.) 

So, while In theory "everything is important", I doubt that anyone here has done controlled, volume-leveled A-B comparisons among multiple streamers in a way that focuses solely on the streaming functions, per se, of all the compared devices.  I'd venture to say that the impact on SQ of the streaming capability, per se, probably is somewhere between negligible and unobservable compared to the impact of the DAC and especially the preamp effects.  But I don't really know for sure, and would welcome anyone to point out a good comparison of multiple streamers, one based on some credible combination of metrics and expert observation. 

@tk21 I know it can be tough to accept that streamers make a big difference, and I applaud you for at least keeping your mind open as opposed to many here who just close their minds based on their beliefs rather than just listening.  Most experienced listeners here observe significant differences between streamers and that they’re at least as important as the DAC they feed.  Darko did a head-to-head comparison of several streamers a while back and found significant differences in sound quality so might be informative searching that review out.  My advice: Trust your own ears and come to your own conclusions because that’s really all that matters.  FWIW…

I did a quick search for Darko's streamer reviews.  Not sure I found the one @soix cited.  Anyway, Darko's highest praise seems to go to the Logitech Squeezebox Touch.  You can get one of those on eBay for less than $200 (US).  I wonder if anyone here has heard a significant sound quality improvement in going from the SBT to, say, the Auralic Aries G2.1 ($5699).  Not necessarily 30X better ... but at least noticeable to the average listener.

@soix +

Resolution, transparency not the most  difficult aspect of sound quality to achieve with streaming. Yes, noise, both external and self generated can enter at many points, but even with less than best streamers relatively high resolution, transparency can be achieved assuming one has decent dac.

My experience has found timing greatly impacts digital sound quality. Get the timing right throughout entire streaming setup and the closer one gets to positive traits of analog. Correct timing allows largest soundstage, most stable imaging, and most importantly, greater sense of ease, relaxed musical experience. Jitter is what gives digital it's bad name, and the reason some maintain vinyl superior to digital. New custom build streamer I recently purchased was built with parts and components specifically chosen for lowest latency, low latency means less jitter. Using the same dac as with prior streamers, greater levels of resolution/transparency has certainly been achieved, but sense of ease or analog like sound qualities has been revelatory.

I observe ever decreasing levels of measured jitter in digital components, certainly large measure of why digital continues to improve.

Another critical thing to remember, you can never get back what has been lost earlier in streaming chain. No dac can clean up noise or jitter created earlier in chain, just as optical with it's total galvanic isolation can't restore whats been lost in regard to noise, the jitter manufactured within streamer has already contaminated the bit chain, even the finest asynchronous clocks in dacs can't restore whats been lost prior.

There is a reason why the best streamers attain higher levels of sound quality, lower latency/jitter and self generated noise. If dacs could really restore whats been lost streamers would all sound the same.

Finally, I presume digital at some point in future will finally surpass the very best analog/vinyl. Audiophile and/or digital engineers are paying close attention to these latency issues within digital components, Ever decreasing jitter will be achieved in future components, this along with ever decreasing noise will further improve digital sound quality.

@tk21  @soix  I think two different setups are being discussed here.  My take is that tk21 is talking about not hearing the impact of a streamer in an all in one unit. So yes who knows if any difference is due the DAC or the streamer, or parts , or implementation within the "streamer".  Most of the other posts have been about streamers separate from the DAC , so  if one is using the same DAC, streamer output to it, and cables  it obviously allows for a notable comparison.