I'd like to clarify a little.
Each channel is a fully balanced differential amplifier. So the amp is not a bridged set of mono-amps, but a real diff amp (or pair of diff amps). Thus, each channel is a single board.
Gain switching is easy for a production unit. I expect that the enclosure itself will be the heatsink and I have mostly figured out this arrangement. Thus, the amp shouldn't be very tall, but this awaits final design and other considerations like the power inlet and volume control, etc.
Assuming that the proto performs as expected and that there is enough interest a production run could be made in the Spring.
longbowbbs the 30 hour days are getting longer.