Unless you have separate components (preamp, power amp digital effects processor, headphone amplifier, an insert loop, mixer etc.) I don’t know of a way you can do that with your existing equipment and even if you did, getting the timing between your headphones and the speakers perfect would be a challenge without spending a good bit of $.
Delay RCA signal
I have a bluetooth audio-technica record player. The bluetooth headphone output is delayed from the speakers when it is digitized. This gets annoying when I want to walk out of the room for a little bit.
Is there a way to delay the RCA signal from my record player to my receiver so that I can sync it with the bluetooth output?
Ideally I could switch this on and off such that it doesn't digitize the sound when off.