With yamahas use of two key power scheme, one key for ON and another for OFF, you won't find a single code in the directv remote that does both, sorry. So if you were testing the codes with stereo on, and code only had a ON command, it would seem the code didn't work. So test ALL codes with receiver on & off.

As for the volume, it NEVER works initially with ANY audio code, reason is the volume keys won't work at all without a tv code programmed to the tv device. Once there's a tv code, its volume is now in the way, but that can be remedied;

So tv code programmed in, a yamaha code that partially controls the stereo, to get the volume in a single device:

1. av1 or av2
2. press and hold MUTE & SELECT, wait for two blinks, release
3. enter 9 9 3
4. press VOL DOWN

in all device do the following instead:

1. av1 or av2
2. press and hold MUTE & SELECT, wait for two blinks, release
3. enter 9 9 3
4. press SELECT