Yep, that's a big room. Not surprised the M3s have trouble playing your rock tunes at a decent volume.
My M2s had the same problem -- they sounded great unless I tried to fill a big room with loud music, then they started to sound "choked". Not a speaker problem, just small speakers in a big room. The M60s fill the room up just fine (with M2-like sound) and the M50s should fill the room up with M3-like sound.
M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
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