Why not just use the internals on the D50? They are quite good. If you are set on using externals you really would be better off getting something like the Church Audio mics or similar.
The internal mics are quite good.
They are *excellent* for ambient recording. Very detailed and realistic sounding. Excellent stereo image. Very low noise too.
For music, I don't like them as much. They sound a bit "harsh" or "edgy". OK, but I like several other mics better.
The preamps are just great, with internal or external mics.
Richard