I also have an HK 3490, with the TV's optical out going to the receiver.
This same thing was happening to me, and I found a workaround for when it happens. Simply switch inputs on the TV back and forth, and it should be normal again.
If he's going to be walking/bussing with these, he won't want a pair of open-back headphones. One of the most recommended pairs of closed-back cans is the ATH-M50. I'd check those ones out.
Probably unrelated, but I have the HK 3490, and it has a pretty noisy headphone output, too.
I think Harman Kardon probably puts most of the effort into the rest of the components.
Honestly, if you're not planning on doing any engineering with them, you're better off spending your money on a decent amp and passive speaker combo.
You'll get more quality that way, especially with a pretty hefty budget like that.
Quote:Originally Posted by mosi *edit*
I had a quick read on the LPF in the manual of your sub. You probably already know but if you have hooked it like rig->receiver(LFE out)->sub(LFE in) that LPF knob is basically disabled and the...