The API probably sounds more present because it's about a dB louder on average (-7.93 and -9.15 dB RMS compared to the RME's -9.14 and -10.17 according to Sonalksis FreeG). Turn it down 1 dB for your comparison and you'll notice the difference is pretty much negligible. You'd get a waaaaaaaaaaaaaaay more noticeable difference just by moving the mic a quarter inch.
well you should always match the volume for a comparison.
to me the difference is still the same.
but yes, it's not night and day, and of course moving the mic makes a bigger difference (but that's not what a comparison like this is about, cause even after moving the mic, swapping amps etc the difference will still be thereand add up dramatically in a busy mix)