Tubes with Infinity IRS Betas

The IRS line was um, problematic. The crossovers were designed empirically through trial and error, amplifiers be damned. Here's the measurements from Stereophile:

https://www.stereophile.com/content/infinity-irs-beta-loudspeaker-measurements

It's not so much the power as the wavering impedance curve with a low of 1 Ohm, far lower than most tube amps recommend, and the wavering  interacts poorly with tube amps, in the sense you won't hear a flat response anymore.

I might suggest you see if anyone has produced a better crossover for these speakers. If so, I bet they fixed the impedance issues. Otherwise, stick to beefy SS.

One tube amp designed specifically for problematic low impedance loudspeakers is the Music Reference RM-200. It even has a 1 ohm tap! 100w/ch from a pair of KT-88 or 6550 tubes/ch.

I recommend a new set of x-overs from dstechlabs.com (Fort Lauderdale, FL).