I can only say that as an early adopter of a computer music server setup I've owned more USB DACs than I care to admit. I'm not sure why I chose the USB DAC route vs. other interface options. I was probably influenced years ago by the content on the Wavelength website and have found no reason to change. I use a Mac Mini with an external 500GB drive with music ripped in AIFF format.
My comments that follow are only to compare USB DACs to USB DACs as I have no basis for comparison to vinyl or other PC interface options (i.e. TOSLINK). I also have no affiliation with any manufacturer as over the years I've purchased USB DACs from Wavelength, Bel Canto, UltraFi and db Audio Labs, all at list price. For completeness the specific USB DACs that I've owned or auditioned (in chronological order) include the Wavelength Brick and Cosecant ver 2 (both non-async models), the Bel Canto DAC3 (using the USB interface), the UltraFi iRoc, and I auditoned the USB interface on the AMR CD-77. I currently own the Tranquility USB DAC from db Audio Labs which is the comparison basis for this post.
I don't have any formal training when it comes to understanding tech specs and I don't claim to have a trained set of ears. My evaluation is mainly based on what sounds good on my system. During my USB DAC journey over the past 2.5 years my system equipment has remained the same with some skr and i/f cable upgrades.
With some of the DACs that I've owned I would typically try to find songs that sounded good on my system rather than listen to the songs that I enjoy. What I experienced was that some DACs made the music sound lifeless as the music lacked dynamics. I also had a challenging time getting a low noise floor with some of the DACs even after following the 'best practice tips'.
With the Tranqulity USB DAC I now find that I've forgotten about the equipment in my system and can enjoy listening to songs that I like. The Tranqulity DAC is dead quiet but as soon as a musical source is applied is when the enjoyment begins.
The Tranquility possesses the dynamic range that we've all come to expect from any gear that we allow to part of our systems. Bass presentation from the Tranqulity is terrific. By comparison bass was totally void with the Wavelength DACs. The Bel Canto DAC3 reintroduces bass but it tends to be a bit muddy and at times gets in the way of the music. Improved bass with the iRoc and the AMR-77 but none of them compare to the Tranquility as you swear it's coming from a source different than your loudspeakers as the seperation from the other instruments is uncanny. Same high praise for mids and highs from the Tranqulity.
Enough about bass, mids and highs. Here's what's really interesting. I'm hearing new artifacts in songs that I've listend to hundreds of times. I think it's due to the sense of having much more space around the instruments creates a huge soundstage that provides width, depth and height.
I'm particually critical to the sound that should be produced when a drumstrick strikes a cymbal. This is the first DAC that gets that sound correct as well as the natural decay of the cymbal. If any of you have the Al Dimeola song 'Flesh on Flesh' listen to the splash cymbal from the 3:45 to 4:00 point in the song. With my previous DACs, this was a bit painful to listen to as the splash cymbal seemed to collide with other musical notes of the song. Digital harshness may be a term used to describe this. The Tranquility DAC is the first DAC I've heard that allows the splash cymbal to be heard correctly and seperately from the other notes. I now find myself enjoying this 15 second musical crescendo.
I've come to realize that the PC Audio area is so new that thinking I've found my last and final DAC is not reasonable and actually not what I would want. The good news is that you don't have to spend a small fortune anymore as the maturation of the USB DAC market has raised the sound quality and the introduction of more manufacturers has lowered the prices. This may sound counter-intuitive but I can't wait to hear my next DAC as they keep getting better.