Back in early 2015 I bought the Spatial M1 Turbo about a month before Clayton released the original M3's to mate with my Line Magnetic 518IA amp (845 tubes). The M1 Turbo is pretty much the same thing as the M3 Turbo S, just with a more expensive to manufacture baffle that is probably better damped than the M3 baffle. At least, that's what Clayton told me when I asked him why he didn't tell me before I ordered the M1 that he was going to release a much less expensive equivalent to the M1 in the near future.
It sounded good, for sure. But I blew two 845 tubes within a few months. The first was one of a used pair that a local buddy loaned me. Not sure how many hours it had on it, but they could have been closer to end of life. The second one was a brand new Psvane 845WE, which Grant Fidelity replaced since it was under warranty. At the time, a friend and I had inquired of Clayton quite a bit regarding impedance curves and had a bit of hard time extracting the info from him. He just kept insisting the speakers were good with tubes, generally. But later we learned they do dip below 4 ohms in the bass frequencies, which made us wary of the match with tubes.
Anyway, I'm really not sure if the tubes blowing was due to the difficulty of the M1 load, or due to the age of one tube and a quality control issue in the other tube. But it made me suspicious at the time, and when I nabbed some used Daedalus speakers at a good price, I sold the M1's and never looked back.
The fact that Clayton subsequently designed the Triode Master version of the M3 to be a better fit with tubes also makes me think the M3 Turbo S is not the best match with tubes. And 845 tubes are darned expensive to experiment with in this manner. Therefore, I'd be hesitant to recommend the pairing you're envisioning, though it did sound good.