This is arguable but to me the difference between decent and great conversion is probably one of the smallest qualitative differences in the gear chain. Mics, preamps, room, monitors & monitor controller (yea, seriously) in almost all cases amount to a much larger difference in sound quality.
You'll find so many people at the high end saying the usual 'RME is brittle, cold, harsh. Mytek, Lavry, Benchmark, Lynx, Prism are more 3d, more defined image blah blah' but seriously with the sort of monitoring and recording techniques many of the home studio guys here use, it doesn't matter in the slightest. It might account for 2% difference in their work, if they can even hear it.
The amount of money from decent (read: not shit) to great conversion is simply the epitome of diminishing returns.