Digital Audio Output Differences? Is USB Audio Really The Top-notch?

As @sns points out, generally speaking "most dacs optimized for usb these days" is true. I would dig deeper into your Silent Angel "streamer" to see if there is a clear preference in output by the manufacturer / owners / reviewers.

Personally, I would prefer to see a singular approach to maximize BOM for a dedicated / optimized output...however, this is very limiting for the manufacturer as it ’niches’ their product.

Grimm Audio, is an excellent example of this. They have done a fantastic job with AES out, but had to add Coax to suit more users.

I’ve spent the last few weeks considering mid to upper tier servers/players and eventually narrowed my options to those that are singularly focused on USB out since my DAC is, per the manufacturer, optimized for USB.

And if the USB Audio can provide the " best " digital sound quality, then why added other ports? Ain’t that just costing more on the manufacturing end?

BTW, I was careful in my use of "the receiving component" in my initial post, so as not to exclude DDC components (vs. simply stating >>> to the DAC).

If, for some reason your DAC and streamer are not optimized around the same Input/Output then a DDC is a solution should you want to maximize performance.

Other companies do this, but since I am familiar with Denafrips, I’ll use them as an example. Their DACs, per owner feedback, etc. perform very well using the I2S input...which makes a strong point for using Denafrips’ DDCs so that one can use the DDC’s I2S output to max effect and benefit.

Finally, there are advantages to using the same manufacturer's server/player/streamer, (DDC if available), and DAC as they are already optimized to work together.

FYI, the Pro focused manufacturers tend to optimize around AES.

You are asking a seemingly simple question in a complex field.

yes, USB >> SPDIF (or its kissin' cousin, AES) - but only if its is implemented correctly.  Or if the SPDIF is crummy (usually true) or....

So while i would begin with USB, you now need to make sure you have clean power, clean (isolated) ground and a DAC with a good clock since it is not the only thing with a meaningful impact on jitter.  Most modern high end DAC do pay attention to both.  How good they are of course varies.

If cables sounds different, there are serious problems.  Some really are that bad, but its usually something else.  Note that almost every "coax" SPDIF cable on the planet has an improper termination - RCA plug are almost never 75 ohm characteristic impedance.....and it just gets better :-)

I have a RME adi2 DAC , it’s a great sounding DAC to be sure....   I use all three inputs and honestly I can’t tell the difference between my coax and the USB.  It sounds so good from all three , it’s like splitting hairs.   

I2s is the best connection in my limited digital experience but finding equipment from different manufacturers that will have the same I2s configuration is a challenge. I don't stream but tried connecting the ps audio pwt to a gustard x26 pro to play my CDs with zero success. Now I switched to the Jay's cdt2 mk3 and the I2s connection to the gustard is fully operational. The sound is frankly so close to my analog rig now, it's hard to tell the difference. And I have twice the dollar amount invested in my analog rig vs. the digital one. I am completely sold on I2s when feasible. And I also want to take this opportunity to thank the digital audiogon community who steered me in the path of my digital journey. Without it I would still be mainly analog. And CDs are so much less expensive. Today I ordered $120 of CDs on discogs including shipping and I am getting over 10 CDs for it, about a third of what vinyl would have cost me and some titles don't even come on vinyl. This is a huge step forward for me. Sorry for getting off track here but just got through an unreal quality CD listening session tonight and felt like sharing.