class D design amplification is a newer technology that has
revolutionized modern small amp systems
the roland (battery powered) CUBE series is a great example of an
entire line of various sized amps based on this tech
several of them are small enough to take apart and re-purpose
as some custom built in job, like the "mobile" cube, and the
original micro cube is also easily re-purposed
(that was what i used to re-build that old Bell and Howell mash unit speaker
into a portable PA for vocals)
the issue in an accordion will be stealing space somehow to make the
baffles for the speakers.. the larger the baffle, the better the low frequency
response. Look inside an FR-7 or FR-3 and you will marvel at how the engineers
efficiently used the internal space..
if you do this successfully, without losing tonality and frequency
response on the accordion, you will gain the ability to unusually
add FX to a strolling portable accordion
good luck