Astrid I use a DJ Tech 50 watt battery/mains amp (from Maplins - which has radio mic if we need it) and it and all our kit, including chairs) is on a converted shopping trolley that we can just wheel in to the room. The amp is really just for my rather quiet tenor guitar, Astrid's accordian usually does not need anything, but she always has her pickup just in case. Picture of set up HERE