Infinity Irs Beta

I recently purchased a set of the Irs Betas. My system consists of a Krell Kct Preamp, Krell Kps28 CD player, Krell Fpb400 cx which I am powering the mid,high panels and using the cast interconnects between them and a Krell Ksa300 for the bass towers with the servo unit. Would tubes on the top end be a big improvement? Any folks here run tubes on their Betas and have you compared the two? It sounds wonderful as is.
Isn't the "IRS" also known as the IRS V (5)?
While attending technical school (around 1983) I joined a group of EE's for a tour of the WFMT studios in downtown Chicago. WFMT had a recording studio/hall with a pair of the gigantic IRS modules 10-15 feet up on the walls.
BTW, we asked the head engineer where he attended school.
His reply: "Self taught". -Mind Blowing!
The last version of the IRS was the V (5), but the IRS series all started with the IRS I, then the II, then the III, then the V. There wasn't an IRS IV.

They are indeed MASSIVE speakers and sound that way too. I've heard them several times and the word DYNAMIC always comes to mind.
So good to see Sirspeedy back in the rooms commenting again! Yes the IRS Beta's are a fine (great?!) speaker. I have the model before that one (The Infinity RS-1B's). I agree with all the comments above. Tubes on top/SS on bottom. I have used Audio Research VT 100 and Hurricanes on the top and now MacIntosch MC 275 (2 of them in mono @ 150watts per).

RWD (Rick)
Paul McGowan (PS Audio) owns both IRS Vs and Betas. He is friends with Arnie Nudell and has done extensive updates to his Vs. He has not mentioned working on his Betas. From Paul's website here is an interview with Nudell where he mentions his own preference for tube amplification, at least up to a point.
The last IRS I heard was at PS Audio in February 2014. They hosted the Colorado Audio Society meeting so that they could show off their new DSD DAC.

If you guys ever get a chance to hear these monsters, it's truly an experience not to be forgotten.

I've heard their Beta's too. Still one of the best.