I own the MA3 and am very happy with it. I replaced a just slightly cheaper (MSRP wise) Mojo Audio R2R NOS DAC that I also really liked. I think the MA3 offers many of the same sound qualities as my Mojo did, and just takes a few of them further allowing me to hear more yet into my favorite recordings.
If you throw in it unfolds MQA, has an integrated Roon capable streamer, Meitner's digital volume control, and is made and serviced in North America, I personally think it is (relatively speaking in hi-end terms :)) good value at the used/street prices it goes for.
I do agree that I think it sounds slightly better with a decent quality external streamer. I'm using a Bricasti M5 with AES and I prefer it slightly to its integrated streamer. If I didn't already have the M5, I don't think I would rush out to buy it.
I think this review https://audiophilestyle.com/ca/reviews/meitner-audio-ma3-integrated-da-converter-review-r1086/ is a pretty good representation of the MA3 based on my experience with it.
Of course, YMMV...