Keen Humfree2 taken to a new level questions

[Unclerny]

Hi Forum, sorry I haven't been around, just buried.

I;m looking at the Humfree2 switcher that R.G. Keen has on his site and I'm wondering how hard it would be to make this thing switch FOUR amps with a Y to combine two active amps.

Here's what I thought would work so far but I'm not sure how to work the Y feature.

First buffer then split the signal to two of the AB circuits just like he has designed and then have a Y that would select just one amp or the two selected amps on the two A/B switches.  That sounds about as clear as mud!

Ok a/b on one switch, c/d on another, then a switch that can send it either out one of the above mentioned switches or both the switches.

I suppose a 4dpt with no LED would work but that's not very practical since they don't exist

any suggestions?

Thanks Tim