Acoustic Solutions 5.1 No Output?

I have an acoustic solutions 5.1 amplifier that has stopped working. It switches on and appears to be working fine but the only output I get however its connected (it has analogue phonos and coax/optical) is very quiet and distorted, I am thinking that the actual amplification circuits have gone but I do not know how to repair them. There were a couple of large capacitors that appered to have leaked and I have replaced them but to no avail.