(Not sure if this is a receiver or a sub question - hope you can help) I've changed amps from a Yamaha A5 to a Denon 2105 because there seemed to be problems with the sub output - i.e. there wasn't one most of the time. The sub wouldn't wake from standby by itself and would go to sleep after 15 minutes as if there were little/no signal going to it even at quite high volumes. As I'm using a sat/sub combination there should always be some signal. Running the sub from a line level tape out - it seemed to stay 'awake' so I figured the amp was bad and the sub was fine. (I knackered the A5 plugging it into the sub with the power on fried the 'mute transistors' according to Yamaha on email - resulting in a nasty thud and nothing more from the sub output. Time for a new amp.) Unfortunately I'm still having problems. I need to turn the Denon master volume up to around 0dB to get the sub to wake, then turn it down and a few minutes later it will go to sleep as though there were little or no bass input - even though it is making a noticeable output. If I play a bass heavy CD or the test tone then it stays 'awake' for as long as there's a signal but as soon as you stop it stands by. I've tried increasing the sub output to +12 in the amp settings and lowering all the other levels to bring up the master level on the amp. I'm beginning to think the sub has a problem with the auto standby function but unfortunately there is no permanent 'on' switch. I would replace it but I'm worried that it's actually the amp has a very low output level and I could end up shelling out for a new sub and wind up with the same problem. Anyone got any suggestions I could try to keep the sub awake by a change to the settings on the amp?