I've owned many JBL's, and yes the horn loaded speakers are "shouty". The 1400's I own now are an exception.
Part of the problem is that JBL's are dynamic - little sound compression on transients, this can be tiring. Exhilarating but fatiguing.
I don't have a solution, maybe class A or tubes. Your speakers are very efficient - you don't need a very powerful amp.