I just happened to come across this thread, and thought i'd let you guys know that I spoke with JBL about these, they are 220V Export models and the MPC200 and MPC300 can easily be rewired for 120V as they are internally wired to handle 3 voltages (100V japan, 120V america, and 220V europe) The amps were all made by QSC, and the MPC200 is the same unit as the QSC CX4 and the MPC300 is a CX6. I posted a thread at the HT Forum in DIY about these at:
http://www.hometheaterforum.com/htforum/showthread.php?s=5d83e443f45681fc52aae4289b2a8976&threadid=131425
and i also posted the modification to convert them to 120V as described by JBL at:
http://www3.sympatico.ca/bonaz/JBL/JBL-MPC-230V-120V.htm
I have not done any of these modifications myself, and i don't have any info on the MPA units, but i hope this is of some help...
Rob