[barb]

Thanks everyone – I am making some progress!
Gregg Myers sent me a transformer which now makes it so I can hear the melodica through different amps without cranking everything up and getting tons of feedback. None of the amps I currently have access to have XLR input. (I know, some day I’ll get the right amp!)
The inline transformer is a 600 Ohm to 5Kohm impedance matching transformer. It is in 2 parts, a XLR male to 1/4 mono female adaptor, and a XRL female to 1/4 male line matching transformer. The first XLR male part says low impedance along the side.
Gregg has been consistently helpful.

I have used a Road Rickenbacker R25 12 inch, Fender Rumble25 v3 1×8 25w Bass Combo Amp with overdrive (works great with Hammond bass melodica), and a Kawai KM15 desktop kybd monitor (which is the least fussy for feedback, and picks up more of the effects).
I think the melodica is already a loud instrument, so am not looking for a lot of amplification. But I like the ability to tinker with EQ, delay, reverrrrbb and pitch shift (for doubling the bass an octave lower).
I have an Elements FX multi effects pedal for learning about effects, which is cheap, works good, and incredibly versatile. I have been testing each melodica – hyper, 44, Hammond bass and SS27 super soprano (could anything be higher!?!); Suzuki M37C, MX32, bass and yamahas with Gregg’s pickup. Am keeping track of how each melodica reacts to effects and creates feedback. As suggested, I started by standing in the next room and gradually coming closer to the amp.
I too have found that some effects reduce the usable dynamic range, which i don’t want – I play melodica BECAUSE it plays loud and soft and crescendos etc. I also find the Hammond 44 to be better than the hyper for effects. And suspect that i will be narrowing down to 2-3 melodicas that I will use with pedals.

B