A 4 or 6 channel SYS would be AWESOME. In the form factor of a bifrost.... drool. The draw of the sys is it does not change the signal it just allows a clean path of switching with no magic or amplification which i can then feed its outputs directly into the preamp of my choice, in this case a Valhalla 2 would be the choice. I cannot do this with any typical preamp I would have to have two preamps or possibly a bunch of daisy chained sys's neither of which i want to do so my purchase of Valahalla2 is on hold until I can find a solution.
Two thoughts for you:
The "Tape Out (Record or REC)" on vintage gear (pre amps, intergrated amps etc.) are generally passive pass through. Example - computer to dac to intergrated amp used for headphones - tape out (REC) to aux in on another pre/amp system for speakers. Speaker system gets unaltered signal from first amp/pre without turning first amp/pre on, just passes signal to the speaker system.
The Pioneer U24 Program Selector is the granddaddy of passive switching, no volume control, just switching.
http://www.thevintageknob.org/pioneer-U-24.html
Be creatative with the tape outs and power amp outs and you get many configurations to play with.