Over the weekend I built a headphone amplifier and swapped the line-level cables from my passive monitors over to the headphone amp and made the realization that I need to be able to switch these remotely. I really don't want to have to keep switching them by hand. I also need to be able to switch my SPDIF/AESid cables between my converter and my digital monitors too.
So.. Maybe I'll come back to the idea of a monitor controller of some sorts.
Maybe 1:4 SPDIF/AESid switching (Coax only) and 1:4 line level monitor switch. I mostly use my sound card control software to adjust levels so I'm not sure I really care about volume control although TI makes a programmable volume control that looks perfect for such things, but it's not differential, so I'd either have to use two of them or use diff-to-SE and SE/diff conversions. Either way, cost goes up considerably and complexity goes up as well.
I'm looking at options. Relay/resistor ladders are one option, but are quite labor intensive and power hungry if you want to have fine steps. VCAs could be used, but there's too much calibration needed.
I'm looking at some resistor ladder IC's that have excellent performance, but are a bit complex to program for someone who's not really a programmer (like me).
I'm thinking of using an 8 channel chip as 3+1 stereo pairs. Each pair could be coupled for volume and mute control, while each pair could be uncoupled for pan control. The 4th pair would be a "master" volume.
I'm thinking that I could dump the 3 pairs into a medium impedance summing bus and the user could either sum the channels, or use the mutes as a selector system. Headphone output could be taken from the summing bus and avoid the 4th volume stage.
I don't know. This seems like a lot of work! I'd either have to really dive into it and make it commercially solid, or just not bother with it.