my reciever shuts down periodically. It goes into kinda like a stand by mode. sleep isn't on. Is this a heat issue? Its a HK 335
We need some more info:
Do you think it is a heat issue?
Does it happen to both left and right sides?
Are we talking relays within the amp disconnecting the speakers with an audible "click"?
Does the amp cycle in and out of this mode with some kind of a period?
Does the amp seem hot when you put your hand on top of the vents above the heatsink?
I think it's hard to get graceful shutown of both channels without the amp's own protection circuit
kicking in. So I would guess you have a relay disconnecting the speakers with a gentle "click".
If it shuts down for a good reason it's either to protect the amp from shorted speakers
or to protect the speakers from abnormal voltages from the amp.
If it's the latter it's a good chance the problem is very much heat related. Any part, any solderjoint,
any connector... can cause this.