I have been searching, but haven't been able to find anything like this. My old NAD receiver (relegated to the basement), like most receivers, has an output selector switch (A, B, or A+B). This is exactly what I need to connect to the output of my preamp to choose A, amp for speakers, B, headphones, or A+B, both speakers and headphones. (A+B is for when we watch movies, so my wife can listen to the speakers and I can listen through the headphones so I can understand the dialogue.)
I would like to build or buy a switch box that would allow me to do this. Any advice or suggestions? Thanks.