It's nice that your friend doesn't want the violin to sound on a recording the way it sounds to him while he's playing it! That would require a very bright microphone indeed (although such microphones certainly exist).
You (or we) would need to find out what he's actually doing with the microphones, though--pattern setting, distance from the violin, distance from each other, and very important: what the room sounds like. All other things being equal, a small room will never sound as good as a larger one. The smaller the room, the "deader" it needs to be, and the less beautiful the recording will sound.
Also, just to cover all the bases, please make sure he knows that the MK 5 doesn't have in-between pattern settings; it's either cardioid or it's omni. Occasionally someone fails to realize that.