Glitch sound from amp at low volume only

Hi guys

My stuff is:

source DVD LG ps3
amp vincent SP-993 200 x2 @8hom 60w class A
400w @4hom

preamp marantz 8500 7.1

speakers paradigm studio 60 v 4

power conditioner panamax 5300

room size 12 x 15 feet

My problem is only at low volume: I hear a glitch or distorted sound.
I sent the device to the service center and they told me that they have to change the relays in left & right channels. Unfortunatly I received the amp but the problem was not solved

I called the service center again and they told me that I may have a missmatch with my preamp.

Although I checked all connections, the same problem still exists.

Then I moved the amp to one of my friends home and the same problem exists.
So whats wrong with my amp? I need your opinion...

thx for your help

 

Try using a passive volume control between Amp and CD (skip the Pre) or use a CD's vol control (if you have one) then if you still have the distortion you can tell the service center that there's no amp/pre missmatch...Good Luck.

 

could be a case of the source overloading the inputs on the pre and power .....try and use a set of attenuators to eliminate this cause