Geez, my M5s are doing just fine with 12 good watts from LTA.
If there’s quality bass in the recording, it’s rendered in the speaker every time. Older recordings lacking in bass heft can sound bright, alas.
Small room, 11 by 14. Rarely listen above 50% volume.
I’ll add that I’d get the M3s or X series, if my room was any bigger.