Meitner MA-3 - direct or with preamp?

Preamp. It’s a pretty darn good digital volume control but an above average preamp should beat it out. Same with the internal streamer (a quality separate is unsurprisingly better). Nothing unique to Meitner, in my experience this is typically true of all dacs.

I have a MA-3 and with many sources I need to use a preamp, an Ayre KX-5 Twenty.  I did try the MA-3 direct to the Ayre VX-5 Twenty amp and did not hear any difference.