I wasnt exactly looking to have tone/balance controls... i just thought since this is a full blow amplifier, it would need a preamp. The specs shown in the PDF look confusing to me when it talks about the "input" sensitivity. I wasnt sure if i needed a preamp or i could just plug my portable MP3/CD player directly into the amplifier. So basically what im asking is, does this amplifier need a preamp or will a MP3/CD player provide enough "signal" to fully use the amp. thanks