Problems with hum

摘要

After reading the review of the Quad Elite QSP stereo power amplifier in the April 2012 issue of HFNI went and bought one. However, it proved problematic for me as it could not be switched on or off directly from a wall socket without thumps and noises emanating from my speakers. I had the same problem with a replacement and so received a refund. I understand that later ones have now been modified. I have now purchased the latest Quad Platinum stereo power amplifier, which does not have the problem I had with the QSP However, it does produce a loud hum through my speakers when connected to the pre-out of my Sony STR-DA5400ES receiver. It seems to me that the earthing arrangement on the Platinum is not compatible with other makes of component.