The K2 works with a myriad of pres quite effectively - it's not near as picky as many of the mics I've used.

It works beautifully with the Summit 2BA-221. If you can swing a Langevin pre, it's a match made in heaven.

Cheers-

If you are a little more budget minded and want to go with a very tubey old school sound you might try it with a GT Brick. Not sure if it would work for Hiphop - it's a little mushy if you need really fast articulation - but it's a cool combo.

I have a K2 and usually plug into my interface ( motu 896hd ) directly. Sometimes I plug into my dbx compressor first. The preamps on the interface are good enough for sure, so I imagine any decent (100-200$) preamp will be great. I like the ART MPA stuff, simple to use, very warm.