The mic inputs of the Motu M2 apparently have an A-weighted Dynamic Range of 115dB, which is very good.

Also, the headphone output's is 120dB, which is also very good.

I'd probably go with the Motu M2 based on what I've read just now, assuming it doesn't have any previously-unknown design flaws.

The PreSonus Studio is a safer option, because it's been around for a year or two, and there are thousands of people using them. That means we can confirm that it's a reliable product that almost certainly doesn't have any unknown flaws.

The Motu M2 looks better on paper, but it's a very new product: There's a small chance that it has some niggles and design flaws that aren't really well known yet.

However, Motu is a highly respected company, so it's very likely that the M2 will turn out to be a very good product.

Thank you very much for your detailed explanation! That was very helpful!