It had been a while since I first set up the Aries Mini. Couldn’t recall what its internal DAC sounded like. I’ve been running the Mini almost exclusively via USB out into a Schiit Eitr USB/SPIDF converter and then into the Gungnir.
So just now, I used a pair of Morrow Audio MA-4 RCA ICs to connect the single-ended analog outs of the Mini directly to the Freya pre-amp. Normalized volume as best I could using a Radio Shack SPL meter. Even so, it is hardly apples to apples as the analog vs digital connections are very different. The Mini’s digital out is running via an Oyaide USB into the Eitr and then from the Eitr via Black Cat digital coax into the Gungnir; a Cabledyne XLR carries signal to the Freya.
Going back and forth, I compared a few tracks. The sound using the Mini’s own DAC (compared to that from the Gungnir) is not bad but the presentation is a little more polite, a little "smaller". It doesn’t present the same sound stage as the Gungnir. Bass is not as deep either. Overall, and most tellingly to me, there just doesn’t seem to be as much complexity around the sound using the Mini’s own DAC. "Ambience" and dimensionality are a lot more evident with the Gungnir. I don’t know if these differences qualify as "drastic". Initially, it was obvious there was a difference in the sound from the Mini but it took some listening to begin defining what that difference stemmed from. Hope this helps.
Belatedly, I wonder if this is all moot as I see the Aries Mini listed as "sold out" on the Auralic website. I’d also heard in the past that Auralic planned to discontinue sales of the Mini in North America. But perhaps you are not located in NA. Whatever the case, good luck in your search.