Hi,
I've got a defective unit of this integrated featuring about 60w/8ohm and would like to fix it by myself.
The unit power on.
I connected a signal in and, both from loudspeakers, headphones and from pre-out

I only get a hissing noise.
Besides, I hear some bump when depressing pre-amp control switches for balance, volume.
So, at first look I guess it's a pre fault

Any idea of steps to discover/fix the problem and/or places where to get
service manuals???
Any help would be much more than welcome

Thanks a lot,
Stefano