Bi-amping a MC275 with my MC452.

Added comment, I use a Schiit sys to balance the two amps which have different sensitivity.

That’s exactly what I’m doing for music. The arc D 70 powers the mids and highs while the 462 powers the bass. I love the combo. Used with VSA vr 4 jr’s which have built in crossovers which makes biamping easy.

Interesting as i also have a 275 and 301 mono blocks i was considering doing the same.  one noted thing is the factory tubes Mac is using (JJ's) are ok modern sounding tubes but IMO are the weak link in the MC 275's performance so consider changing them asap. they are overly bright, lack musicality and are rather harsh sounding tubes. 

I know from experimenting that the SS mac amps have way better bass control and depth then the MC275. With the stock tubes the SS amps IMO have better top end as well, those JJ's are harsh sounding IMO. The midrange and sound staging is better on the tube amps though.

If you have a preamp like one of the current MAC ones you have the ability to adjust the gain on each output so matching would be easier. 

note sure if buying one to try is worth the money maybe a dealer would let you try it first. As for not working with horns that silly they are tube amps and horn's IMO always sound better with tubes, granted the amps have good tubes in them. maybe more power then needed but I'd say that for both amps your talking about. 

Interested to know how you fair. 

I'm using a MC70 or c22 preamp same unit 

It’s always subjective, but I don’t know of any reasons why the 275 wouldn’t mate well with your horns. Lots of people like tubes with horn drivers, and they give the option of rolling tubes to tailor the sound to your liking. I consider tubes on the mids/highs and solid state on the woofers to be the best of both worlds, but there are many variables in play (like the specifics of the amps and what frequency range each is covering).

Depending on what preamp your using, it should be possible to split the output signal to two amps with the 275 on the mids/tweeters, and the 452 driver the woofers (known as horizontal passive bi-amping), assuming the amps have similar gain. If not, then you’d need a way to control the volume of each amp. It’s worth a try IMO.

Some may tell you that bi-amping is waste unless you bypass the passive crossovers and go with full active crossovers. Both crossover types have pros and cons, and active crossovers can certainly be beneficial in some applications, but if your speakers currently sound good using a single stereo amp and passive crossovers, and you’re not prepared to modify your speakers extensively, they should still sound good using two amplifiers....hopefully it’ll sound like an improvement to you, but that’s subjective.

My bi-amp setup is hybrid, running monoblock tube amps on the midbass and tweeters with passive crossovers, and a solid state integrated amp on the woofers using an active low pass crossover @ 80hz. It definitely made a nice improvement IMHO.

Good luck!