I get what your trying to put together and agree you answered your own question, JBL (biggest and baddest you can afford). Google JBL 4350 monitors. No subs required.
To the posters who think that the Grateful Dead "just" used PA for the sound haven't been to a concert. There is a very good YT vid on "The Wall of Sound".
Funny I don't see any PA. This is a super high end system.
Lastly, The GD employed the best recording technics they possible could and in fact moved the ball the down court. Most of the GD live recordings are directly off the sound board.
BTW Phil Lesh ,bassist, had his own set of amps and speakers for each string on his bass.
Regards,
barts