Quite a few Bricasti M21 DACs for sale cheap

I'm happy with mine.  Going to stream Qobuz now using Audirvana.  Agree with @hgeifman 's comments about the M21.

Bricasti OWNERS ONLY:

The Bricasti web site says “The MDx was implemented in production on all products starting January 2020, and is now available for upgrades. In keeping with our upgrade philosophy, all past D/A converter products are eligible for the MDx upgrade including all versions of the M1, M3, M12, and M21”. 

I asked Bricasti its explain how this applies to my Bricasti M21 DAC.  They said "An updated MDx will gain me nothing sonically. The newer revision is solely for the implementation of the new graphics display and IS2 for the M19 Transport. The M21 is identical sound-wise”.

That is what Joe told me as well when I expressed interest to update the MDx1.09 on M3 to the latest. I didn’t pursue it further as I trust Joe knows what he’s talking about.

To answer the original question, some of these M21 could be floor models/demo units.   And businesses should demo the newest model, with the new screen.  

Anyone that still has the pre-MDx upgrade, it is well worth the money to upgrade it.  Based on my experience of pre-MDx and with the MDx in an M3.  

I currently have an M21 and love it, part of me wants the new display, but without any sonic improvement, i'll hold off.

And to also answer the original question, it could be anything.  People are always selling and buying.  Who cares.  The better question is what DAC’s have you listened to and, more important, what DAC do you really like because it sounds great in your system. 

I own the Bricasti M21 DAC in my main audio system and the Benchmark DAC3 HGC in my 2nd system.