Just a quick note on the hum issue. I've used the Ebtech (now owned by Morley) units for years, and they are great! Signal/ground imbalance in most cases is eliminated, or reduced drastically. There are no switches. Just plug one cable into the input, and the other to the output. There are different models depending on what type of connector you use, and how many inputs/outputs you need. The HE-2 has two 1/4 TRS ins/outs, and runs $65. They also make a 2 in/out XLR (humxlr) model, and an 8 channel in/out rack mount ($225). These are passive devices and really do the job. Sweetwater, American Musical, Musician's Friend all carry them.

Richard