Quad 33/303 hum


Hello all. My first post here.

I'm getting a persistent hum from just one channel through my Quad 33/303. It's at the same level regardless of the volume setting, and is only present when my CD player is connected to the pre-amp, regardless of whether the CD player is powered on or off. If I remove the CD player's power cord from the wall socket then the hum stops.
The hum isn't mega-loud but is nonetheless audible particularly when listening at low volume settings.

So, I'm assuming it's an earthing loop problem of some sort, but I've no idea how to go about getting rid of it. Any advice will be much appreciated.
Many thanks.
darkstarcrashes
I had the same problem from Quad stuff 50 years ago and it bugged the H**L out of me , the worst part was my phono side . It was awfull I was constantly getting hum on every record I played and it took me years to fix. It was those blasted din plugs and sockets that did it because the pins were so close together that the unshielded cables just bled hum to your amp. I had it on 33/303, 33/405 and 44/405 / 2.
The last time I heard it was when someone I knew was getting into hi fi and showed an interest in my setup so i gave him a 44/405/2 and FM3 for nothing. I went onto Meridian then and stayed with it for over 20 years.