Timo is right, the preamp is something else that will distort your sound. With every peice of equipment that the signal must pass through you create more distortion. If however you need a tape-loop, then your forced to a preamp perhaps.
There are many preamps out there to chose from. Very hard to make a recomendation without knowing your speakers, room size, etc. If you insit on a preamp try a well known brand that is a little outdated. That way you will gain some experience, get the feel for a companies basic signature. And if you don't like it, you can usaully sell it without losing money. Assuming you bought it at a good used price.
There are many preamps out there to chose from. Very hard to make a recomendation without knowing your speakers, room size, etc. If you insit on a preamp try a well known brand that is a little outdated. That way you will gain some experience, get the feel for a companies basic signature. And if you don't like it, you can usaully sell it without losing money. Assuming you bought it at a good used price.