Leaderboard

I would be inclined to use a resonator guitar and add a pick up to it, going into something simple such as a Caline Lorcan amp, which is small but loud enough for what you want, can even run without mains for three hours, and has a built in delay effect, then go through an EQ pedal to the Lorcan (up to three pedals can take power from the Lorcan - it comes with the cables for that purpose). In that way, if the resonator isn't doing it all on its own, you can use the EQ to give the pickup on the guitar the necessary frequencies to have it poke through a suitable frequency hole in the accordian's range. I can recommend the Recording King RPH-R1-TS Dirty Thirties resonator, which is comparatively inexpensive (abut 300 quid), but with its spruce top and resonator, it is bright yet has some warmer undertones too, so it hits quite a broad range of frequencies, and if you added a pick up to it, its range could be further tailored to suit you requirements even more via an EQ pedal.