Loud hum/buzz from my left speaker only

I just received my hf-81 and just got done hooking everything up. Okay, I'm only hooking a CD player to it via the AUX A inputs on the back. I'm very clueless when it comes to tube gear so I really need your help.

I've got a very loud hum/buzz coming from only one of my speakers, the left one. The right one seems to be fine. I've tried plugging the hf-81 directly into the wall, which is on a grounded hospital grade outlet and into my topaz ultra isolation transformer. Either way, I still get the hum/buzz.

Please help me,
May simply be a bad interconnect or a bad ground connection with an interconnect. Swap out the ones on the left channel side one at a time and see if that fixes the problem before checking anything else. The make sure the speaker cables are not causing the same type of problem.
First try swapping the tubes from side to side. If the buzz switches sides best bet is a defective tube. If swaping tubes did not help, swap the speaker cable leads from the back of the unit. If the buzz does not switch sides, you may have a speaker problem.