joreth said:
but I cannot get amp output to feed headphone amp, I would very much appreciate any advice. Thank you
I don't think you need an HDMI splitter: the Yamaha amp is set as default not to play sound out through its HDMI output, I guess as it's assumed you'll be using the amp for your sound, and the TV purely for pictures. But you can change this.
If you go into the amp's option menu (item 5 on the main menua) and choose 'HDMI set' you'll be able to change that setting from 'S. Audio DSP-AX863SE' to 'S. Audio Other', which will feed the audio out through the HDMI output, to which you can connect your headphone amp.
So all you have to do is remember to make that setting when you want to play sound through the headphones, and put it back to 'S. Audio DSP-AX863SE' when you want to go back to listening through the speakers. Page 84 of the Yasmaha manual explains this.
The set-up above would be much better than adding another level of HDMI switching into your system: such switchers can be a nusiance at the best of times, and a PITA at the worst, thanks to the flakiness of HDMI handshaking. It's designed to stop unathorised copying of content, but is more often responsible for inexplicable 'no signal' indications and a lot of frustration.