a little while ago i turned my amp on and realized the speaker cable wasn't plugged into the cab. lately i have been noticing my amp sounds very harsh like even if i use an eq pedal and take out all of the high frequency's they harshness is still there.
First suspect is always a faulty tube in tube amps.
First try a re-tube before considering other damage.
What can happen is that the windings in the OT can get punched through with the high flyback voltage.
The wires might not be shorted out all the way but rather when the amp is turned up the wires can arc to one another.
The wire used is coated with a type of enamel that is pretty thin really.
But unless you really punished it without the speaker load, it's probably ok.
I had a faulty speaker cable that drove me nuts.
The center conductor broke on the plug.
I was ready to start ripping parts out of my amp when I thought to try another cable.....
It has worked fine since then.