Quite a few Bricasti M21 DACs for sale cheap

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.  

@kilkil all M3 DACs had MDx boards from day 1.

Have a new M1SE DAC with network card. Stream qobuz via audirvana . Couldn't be more pleased. Robert

The Grimm Mu2 is getting a lot of chatter. You may see some Bricasti owners going that way.