Pragmatic Communication's Stereo In-Wall Amplifier is available with
24 Watts (12 V DC), 36 Watts (13.8 V DC) and 48 Watts (15 V DC) per
channel. It fits in a single gang and has three different configurations.

One
configuration comes with pre-amp level signals and DC power inputs from
the front and a speakerwire connection in the rear. Another is a unit
with only DC power input from the front and pre-amp level input signals,
and a speakerwire connection in the rear. The final option is unit with
just a blank access panel in the front and all the connections for DC
power, pre-amp level input signals and speakerwire connections in the
rear.