Martín Logan choice help

"I was thinking before, that I could get the Magnepan LRS, new and a good subwoofer..."

That would be a better route to take assuming you also get an amplifier that drives them close to their potential. As for Martin Logan panels, in my experience they last much much longer in terms of their sound performance if they are cared for properly by their previous owner(s), e.g., exposure to direct sun, smoke, dust, humidity, etc. I have a pair of ~20 year old Aerious I model speakers and they (still) sound very clean, crisp, top to bottom. Same consideration for amplifier choice applies to Martin Logans as well. My suggestion is consider your total budget and divide it between speakers and the amplifier/preamplifier, source component, cables, etc., etc., accordingly.
Good luck.

Congratulations. Based on my experience with the MMGi model which has about the same dimensions, you may also want to try the Sound Anchor stands to lift them a few inches off the ground. In my room, the improvement in sound quality was substantial. Also, as I’m sure you already know, pulling them well into the room will significantly enhance their sonic presence.
Enjoy.