I had MA3 for about 2 weeks in my system and listened to it extensively using Aurender N200 streamer via USB. As well as using it as a Roon end point connected with Ethernet cable.
I find the Stereophile review of the MA3 to be accurate.
Improvements that I hear with the MA3i are
1. quieter background - this results in better detail retrieval and layering. The DAC is also more revealing and won’s sugarcoat a bad quality recording
2. Highs are sweeter and more natural but still nicely extended. cymbals shimmer with more texture and sound more real
3. clarity in the mids slightly improved due to lowered noise floor
4. bass and dynamics improved
I find the bass on the MA3i to be very accurate and fast. It isn’t huge, thunderous or boomy. It’s articulate.
Soundstage - the original MA3 excelled here. I don’t hear any difference in soundstage width, depth or height with the MA3i but I definitely hear better layering and separation of instruments. Here it’s not night and day difference but it’s an important improvement.
The sound is still very engaging and very musical.
I found the MA3i to sound more to my liking using it as a Roon endpoint. My Roon core is Mac Mini that’s located in a different room. I use EERO mesh network and have an EERO node in my listening roon. The Meitner is fed from EERO using Audience Hidden Treasure Ethernet cable.
I sold the Aurender N200 streamer and the Audience StudioOne USB cable I used with it. Yes the Aurender sounded different but it didn’t sound better. I actually prefer the more lively and exciting presentation using the MA3i as a Roon endpoint.
One other thing to consider in the upgrade that the gain on the MA3i is higher. The output voltage is increased. You can obviously tune it down with volume control but I haven’t found it to be necessary.
My take on it is, if you like the sound of the original MA3 in your system and want more of it and with improved quality then upgrading to MA3i is the right step. If you don’t like the MA3, then look elsewhere.