My guess is maybe. In a small room, you wouldn't want to crank any speaker up because the room would overload too readily. Twenty watts is a whole lot, provided you don't demand extreme volume and expect movie sound effects kind of bass.
I've heard quite a number of smaller, supposedly not high efficient speakers play at reasonable levels in small rooms with no difficulty driven by anything from 5 watts to 18 (single ended and pushpull amps).
I've heard quite a number of smaller, supposedly not high efficient speakers play at reasonable levels in small rooms with no difficulty driven by anything from 5 watts to 18 (single ended and pushpull amps).