The source would feed a preamp. The preamp would be connected to the LFR DSPs/amps and the amp for speaker B. Switching would take place at the preamp level or at the source level.
It would still be a very tough set up to try. I actually have a non remote version of the switching passive pre amp that Axiom uses - Debbie built it for me in 2015.
To be fair in the test, the speakers are set ABAB then switched to BABA. Doing this with the actives would take too long. Then you have the argument about amps ...
Axiom usually uses Bryston amps for the blind tests, along with a Bryston pre amp. It keeps the amp interface "neutral."
My personal preference for a test would be the M5's vs Martin Logan 35XTi ($1300 per pair).
