The 9 volt battery holder sucks :< I’m now using tape to hold it in place since it’s not possible to change batteries (how did I use all that juice!) when it’s affixed. Well, unless you take midiboy apart.
I really like how the Kastle (from bastl) synth solved the battery compartment problem. But thats a 3+ volt solution.
Aside from that, audio out plug I’ve hacked one on:)