A friend of mine just got a (used) cassette 4-track the other day and i was helping him check it out and learn how to use it, everything works fine except the internal mic pre is such a piece of shit that it wont get decent levels out of a mic (a sure sm-58) ... so what the cheapest solution you know of? a used beringer ub502 seems like a decent deal or maybe a used art preamp... any other ideas?