Disclaimer: I am a COS Dealer now!
In my system, the COS D1 bested:
Emm Labs DAC2X (very neutral but not very analog-sounding).
Playback Designs MPS-5 (very analog-sounding but not very neutral).
Bricasti M1 (Impressive build quality, studio type accuracy, not very musical).
Rockna Audio Wavedream DAC (extremely dynamic, not very natural).
Metronome C8 (Open, romantic and seductive, especially with tubes).
I never thought I'd become an audio dealer but the COS D1 is easily my favorite DAC after trying more than 20 DACs $2k~$20K+. While some might think high-end DACs sound similar, my experience is they sound more different than low-end DACs do. The logic behind it? maybe high-end DACs have to have more "character" to justify their price tag; or maybe they tend to use FPGA with custom algorithm which give them more of a departure from the typical "chip sound" (all Sabra DACs sound alike?).
All the above mentioned DACs sound good one way or the other, but for some reason, listening to LP makes me relax, while listening to digital, regardless of format, makes me stressful after a while.
COS D1 is the only DAC that allowed me to relax into long listening sessions without loss of dynamics and excitement. There are many professional reviews of this unit so I won't go into the details, but as a DAC, I have not heard better. It's analog preamp section may be surpassed by my Mark Levinson #52 or Conrad Johnson GAT MkII, but that depends on my mood and type of music too. I can happily live with the COS D1 driving my power amp directly in a simple and elegant system.