Streamer opinion.. Pease comment on validity.

 Not valid.

There aren't that many streamer only devices with no DAC, so it's not easy to compare different streamers into the same DAC.  What I have done is compared the sound of the Bluesound Node 2 with its internal DAC to using my Sony TA-ZH1ES headphone amp's DAC.  There was a noticeable improvement using the DAC in the Sony.  For my other Node 2, I used my Auralic Vega DAC instead of the Node 2's internal DAC.  I never did a comparison between the Vega and the Node 2's DAC. 

While that doesn't answer the question of using different streamers with the same DAC, it lays some groundwork for what I did next, which was to replace the Node 2/Vega combination with a TEAC NT-505 streamer/DAC.  The TEAC, which cost less than $2,000 easily bested the sound quality of the Node 2 into the Vega (which was a $3,500 DAC when new). 

While it's possible that the Vega just isn't that good, or that the DAC in the TEAC is a giant killer, I believe that the difference is more likely due to having better streaming hardware sending the signal to the DAC.  I can't think of much, if anything, in the audio chain that doesn't matter, so it stands to reason that a better streaming source will result in better sound quality.

I would be very interested in a technical explanation of what it is that makes one streamer produce better sound than another.

Well then, this question has been asked in a few threads.  Why isn't someone comparing then if it's so easy?  So far, I think Ozzy is the only one I've seen that's actually done it.

Well said Ozzy.  Whether it's a blind test or a fast A/B sighted test, while you may hear differences, that doesn't mean that you'll be able to instantly pick the one that is "better".  I've heard (and bought) a few things that upon first listen I thought sounded better than something I had, but after extended listening noticed other less favorable characteristics about the sound.  Often it was that very thing that caught my ear which upon further listening proved to be exaggerated in a way that made it hard to listen to for an extended time. 

I'm going through a bit of that right now with my new streamer.  Upon first listen it seems that things sound "better" upsampling to DSD, but then I start to hear an edge to the music that I didn't notice without upsampling.