which is a better match for best results

I heard the Krell Evo 402e with a Phantom preamp, which is the newer version of 202.  It was an excellent result for both jazz and rock.  Of course, your choice of interconnect and speaker wire can always influence things.  Keep away from silver, lol.

auxinput speaketh truth!

which is the best suited pre amp for rock and jazz

Electronics can in no way favor a certain form of music! Can't happen- no how no way.

@atmasphere - well, I beg to differ.  There will be some systems out there that are too bright or with too much silver.  They may be okay for things like jazz (piano trio or quartet), but with rock music, they just get to bright/harsh/thin.

If they are that way with rock, they'll be that way with everything else too as soon as it gets complex. The kind of music won't matter.
This is without any doubt the most common myth in audio- that equipment favors a certain kind of music. I had a guy ask me one time what the best amp for downtempo 80s was. I'm pretty sure he was serious, but if not he totally got me.