That first A/B was a nice read Mike, thanks for posting it. I've heard that MA series and it's an excellent monitor. However, the second A/B? C'mon now....Infinity Beta? They stopped making good loudspeakers over a decade ago. Just an opinion guys, don't freak out.
I affectionately recall the Infinity EMIT-R tweeter and the....ugh, a very nice series that I can't recall off hand. Reference Series maybe? The cabinets has a corrugated cardboard side panel look...ring a bell with anyone?
The IRS monoliths are pretty killer but that isn't a "normal" speaker, as much as a space eater with divorce written all over them.
Mark
Polk Audio CS