Think my next step is going to be trlo try to trace the offset back through the DAC, the op-amp buffer to the switch, and the switch itself. Thinking about it the offset appears when the sources are switched in - when the switch is muted the offset disappears, therefore I *think* this implies that the analogue bits after the switch are not the cause here. I'm still not sure why this isn't being filtered out down the chain but the good news I guess is if it is the DAC, the opamp buffer or the switch, I have spares of these on the bad HDMI board, so this is now a project for when I get the time...

The problem is present irrespective of whether PD is enabled.

I have to say though that I'm now thinking this has to be an analogue issue and I've just been very unlucky to be in possession of two amplifiers with very similar analogue errors. The front right signal is buffered through a DAC on the HDMI board and goes through an analogue switch, but this is buffered to the preamp board via a series 47uF cap, so surely any offset present at the digital, or DAC stages should be removed at this point right? I've checked these caps and they're fine, on both amps.

I just find...

I have a TX NR414, well I have two actually which are both exhibiting the same issue.

The one I've had since 2012 developed DC offset of around a volt under load on the front right speaker output. Not enough to trip the protection but enough to be noticeable in terms of sound quality. I checked the preamp board and couldnt see anything obvious. The offset is too high really to be a drift issue right?

I put the amplifier away for a while. I managed to pick up another example with a dead HDMI board very cheaply (common on these - mine was replaced by Onkyo several years...