To @whiteknee - while I cannot speak to the Toolshed amp, I've owned several Cary and DH Inspire amps, EL34s, KT88s, and KT150s mostly. They are different amps from the QS mid-monos, which should have more grip than the PP SLA70, imo. I'm not a huge 6550 tube fan person but they do sound different in different amps, most of what I've heard with them is a more "glassy" sound, and I'd probably take really good EL34s or KT77s over them in the Mid Monos. However, that's just my opinion and I've not heard your amps on the Omegas, yet a friend owned the Omega Super Alnico Monitors, and tried so many different tubes with 4 different Dennis Had Inspire amps with his Alnico Omegas. He liked 6L6s a lot with his horn speakers, and he's the guy that originally got me and a few others to try KT77s.
Hard to say really without hearing your setup, room, amp/speakers. What tube characteristic do you want more or less of, etc. I can understand why you might want to try different tubes with those amps and your speakers. Seriously, I'd contact Mike. He uses big Klipsch to develop those amps. Ask him what the 2nd-next tube to try in your Mid-Monos might be and tell him about your speakers, send a pic, he can help give secondary ideas. I'll be curious if he just says to stick with your Tesla EL34s, LOL :)