I believe that the McIntosh MC402 has enough power to drive the JBL speakers effectively. However, if you want monoblocks here are the concerns.
1. If the speakers have internal crossovers that cannot be bypassed, it is a good idea to use identical amps or amps with the same power ratings. If the amps have volume controls then that makes it easy to match levels.
2. If the speakers have external passive crossovers, then you can obtain an active crossover which high/low level adjustments and you then don't necessarily need absolutely identical amps.
IN any case, you definitely want to take these home and demo them in your system in your home before purchasing.
enjoy