Jafant, I do hope you get to hear the STR with your Thiel’s before committing to it.
I wouldn’t exactly agree that it’s “very powerful”, not with your Thiel’s at least.
Look at the specs below 4 Ohms, both the integrated and the SRT power amp seem to drop current output fairly dramatically (for ss) below 4 Ohms, which is where your 2.4’s reside from 100 Hz straight through past 20 KHz. Below 100 Hz the 2.4’s impedance curve is a bit of a roller coaster ride with some challenging phase angles too. It’s power output below 4 Ohms is comparable to a less than 138 Watts per channel amp that could truly double down to 2 Ohms. Of course, depending on room, source material and desired listening volumes, either could be satisfactory.
Personally I would be concerned about depreciation purchasing one of these new.