In your price range about the only thing I have to suggest is something along the lines of the Paradigm Monitor 7's that I use in my Home Theater. I originally bought them for a 2-channel audio setup and liked them for straight music very much. They are full range enough that they do not require a sub. I can in no way vouch for them sounding better than the quads since I haven't heard any of them.
Sounds insanely complicated to me if you want a physical switch to be able to do it on the fly. Even if you leave the switching of the power to a passive device (say, different umbilical inlets for the different amps) you're still stuck with how to switch the inputs/pot so that they feed the right amp. At least I don't think you'd just want to wire them in parallel with each other. But I freely admit I've only given this about 2 minutes of thought and it deserves a lot more.
I think you're over-generalizing just a bit here Marc or perhaps I'm over-reading your comments? Dual chassis designs have their pluses and minuses just like single chassis builds do. Saying that "serious designers" saw issues with it and are now moving away from it because all it represented was some FOTM/fad is pretty presumptuous. I'd love to see internal pics of that preamp to see what sort of shielding the transformer has.
The 12L actives have an XLR input on the back so my guess is that he's running them with a balanced preamp. Most subs want a single-ended signal so the cabling of such an arrangement could get complicated. At least, that's the only logical thing I can come up with.
Sucks for both of you that I'm working on your betas then, eh?
In other news Nugget Audio is pleased to announce that we have begun accepting bribes, er, preference payments for those customers wishing to see their projects completed sooner rather than later.
I believe the heat sinks on all of amb's boards are 100% isolated. Yes, they have solder pads and thru-hole plating but they are not tied to the ground plane that I can see.
I heard a brief news story yesterday on a cool app but don't know the full name. I think it's Iphone only but allows you to listen to any of like 400 NPR radio stations. KCRW in Santa Monica alone would make this worthwhile.