I listened to all the samples, and hear this low frequency wobble/warble kind of thing that I'm not a huge fan of. It's present in all of them, which means it's part of the mic, not a characteristic of a specific pre. Do you hear it? Any thoughts?

It's enough to put me off using a mic like this on a male voice, and maybe a female low husky alto too. It might work better for a higher/lighter female voice.

I think I've previously mentioned that generally speaking, I'm not a huge fan of M-Audio (especially older M-Audio which can be horrifically bad -- though things have gotten better since the Digi/Avid acquisitions/mergers/sleepovers). I'm interested to hear if you have any thoughts on the mic. Did you [try to] use it in any professional situations?

As far as pres go, they all have their own characteristics. The Millenia TD-1 is noticeably thicker than the True P-Solo. The UA Solo 610 sounds very similar to the True P-Solo. The Joe Meek is just a tad brighter than the others. I'm jaded when it comes to this...just because the Joe Meek is a tad brighter doesn't mean that brightness couldn't have been coaxed out of most of the others using their EQ.