Long microphone cable runs are not "bad" per se, but you will notice a difference in overall quality by keeping the mic to preamp cable length as short as possible. If you remember that the idea of the preamp is to amplify a mic signal, it makes a lot of sense that you would want the connection between them to be as good as possible. Yes, even after 30' of so or mic cable there is a tiny bit of degregation in the mic signal that could be improved if the preamps enjoy a shorter cable run to them. Line level signals (Line level being what comes OUT of the preamp) can travel much longer distances without any noticable quality loss. But if you are just recording demo's, you should be okay. I have some pretty decent recordings of stuff that ran 100' through Horizon snake cable before hitting preamps, but admittedly, the tracks that had only 20' runs from mic to preamp sounded clearer and had a bit more presence, and it seemed that the frequencies between 2-8KHz were much smoother.
Good luck.
Ed
