We bought a KAT-2 years ago for this purpose and love it. They don't make it any more, but I'm sure they have an equivalent model. It isn't fancy (and doesn't have to be since it is just for practice) bit it gets the job done. Some will probably recommend some of the Roland models which are really good, but are too much for a practice room. If you were using it live, maybe, but not for a practice room.