My RX-V567 (about 3 months old) has some problem with the sound output. Sometimes when it is turned on, it gets very loud even though the volume is set at around -48 db. And when I turn down the volume, it is still very loud and I have to switched off the unit and power on again. This helps sometimes but not always. I also noticed that the sub-woofer is not working properly.

SOURCE: volume and multi channel output issue

Hi there. Are you familiar with board level repair for such products ? Your problem is most likely hardware. Either some of the final output transistors are fried, or it's a dsp problem, a regulator, a diode, a transistor in the circuit.. it could be a lot of things. But if everything was working fine and it quit someday without a change in the system's setup, it really looks like an hardware issue ! Do you have a way in the manual, that sets factory defaults, a kind of reset ? A lot of such units do have that. Try to unplug/interchange speakers as well, a shorted speaker could make the amp go nuts as well, but i wouldn't bet on it. Still, i'd check that out. Hope that helps ! cheebster.

SOURCE: sr7200 LFE (sub woofer) output stopped working

Chances are if The Receiver only has sound in Stereo Direct Mode and all surround modes and Sub out are Inop the DSP (Digital Signal Processing) Card is most likey defective. These boards are not available from marantz (D&M Holdings) and must be Component level repaired which usually is not cheap. If Only the Sub out is not working check setup to be sure sub woofer is set for on. Also If On Screen setup menu does not appear on video monitor Unit may need to be Reset manually which entails discharging a Capaitor on main P.C.B Contact [email protected] for details

SOURCE: My Yamaha RX-V661 shuts off at moderate volumes.

Try to disconnect speakers one by one and see if any of them causes the problem.

SOURCE: I own a Yamaha RX-V461 and since making a few

You can reset the settings to factory defaults via the Advanced menu - it should be in your manual (I have RX-V465).
Do it from the standby mode.
Press the STANDBY button on front panel (not remote) together with STRAIGHT button on the front panel. Now you are in the Advanced Setup. Scroll to the INIT menu and select ALL.
Now you will have all settings in the default.

SOURCE: i just bought a yamaha

sell the bose sub, buy a nicer yamaha sub, enjoy the 200 bucks you have even after you buy a new speaker.