I'm using a set up with a CD player, DVD player, and Surround sound processor and 2 channel Amp. I use the surround processor to drive the sub, centre and rears with an output to the 2 channel amp to drive the front speakers when using the surround system. I just replaced my existing amp with the Arcam and now I have interference which manifests itself as a low buzzing in the speakers unless the the 'direct' switch on the amp is pressed. This reduces the noise but does not eliminate it totally. I notice that with the direct switch off (such that the controls are not bypassed) adjusting the treble control on the amp has an effect on the interference. also I notice that with everything switched off at the front panel power switches - if I touch the interconnects from the DSP-E800 to the Arcam amp with one hand and the case of the Arcam amp at the same time I can feel a mild tingling in my hand....(not sure if this is normal - does not seem right.) MORE INFO... With the interconnects disconnected from the DSP-E800 the Arcam amp is fine (interconnects from CD to amp still in place) When the interconnects between the DSP-E800 and the Arcam amp are plugged in AND the DSP is unplugged completely from the mains, the Speaker buzz is still present. Even more info.. I've gone right back to basics and set this up purely with my cd player and speakers only - with all the other kit removed. There is, I think, definitely something wrong with the amp. When you adjust the volume there is interference as the volume control is turned. Even if you turn the volume control, with no input from the CD player (IE. switched on but not actually playing the disc) there is still crackling interference as the volume control is turned.(let go of the volume control and it all stops crackling). To sum up... It appears that as soon as anything is connected to the auxiliary inputs, even if the kit that is connected is unplugged the hum starts up in the speakers.... any ideas... looking for advice.... System is, should it be important... Arcam Alpha 7 CD, Arcam Alpha 7 Amp, Yamaha DSPE-800 and Tosh DVD. Mordaunt short Front and centre speakers (bi-wired) and an Eltax active sub & Eltax bipolar rears.