I've spent quite some time researching the market for the best balanced audio interface for my needs - record voice and electric guitar.
The best review I've seen is from Julian Krausse on YouTube, really deep technical analysis and comparison, watch it!
Now Motu M2 may cost above average for this user level devices, but I think it's worth it. It's just amazingly perfect in all aspects, but I'd mention 2 things:
- do upgrade firmware, I did have occasional weird noise in monitoring channels, and upgrade solved it
- power is just enough to drive Sony MDR-7506, maybe it will not be enough for some monitors with higher input impedance, but probably it's still better than other interfaces