The older JBL is not a very transparent speaker. You would be doing yourself a big favor to upgrade. I recommend you consider the JBL LSR speaker. Similar in size to the 4311, the LSR is a thoroughly modern design. It's one of the great "unknown" values in high end audio. In a slightly different direction, also consider the Classic Audio Reproduction (CAR) speaker line. They're high efficiency, horn designed speakers. The Avant-Garde Uno or Duo models should also be on your list. From your post, I suspect you value a speaker capable of high volume levels with an upfront, as opposed to the typical audiophile recessed, midrange. Any of the speakers I mentioned will provide these qualities, yet they'll also provide smoother bass, more extended, cleaner highs and more transparency.
I am nuts to use these speakers?
I fell into the world of "high end" audio by accident. I've always had mediocre Japanese gear with the exception of a Thorens 125 turntable and Altec Lansing speakers. Then I bought a used ARC Ref1 and an ARC Phono 2, tweaked the 25 year old Thorens with a new Goldring cartridge and it changed everything. I also picked up a used ARC CD1 but vinyl sounded so good that I went off the deep end and bought a VPI TNT 3.5 and replaced the Phono 2 with a ARC Ref Phone Preamp. My power amp is an ARC D130. I am using a pair of JBL 4311 studio monitors for speakers and assorted Cardas Hexlink for cables. I think the system sounds great. The JBL's are sitting on some lead shot filled target stands which also have spikes. My room has a concrete floor and I have separate power outlets run from the fuse box for all the gear. Anyhow I think that the speakers which I paid 300 bucks for from a radio station could probably use an upgrade considering the rest of the system. BUT I think they sound great. Basically if the vinyl is great it sounds great, if it is lousy vinyl the speakers seem unforgiving. ANY SUGGESTIONS on where to start looking? There seem to be a million speaker lines out there so any advice is appreciated.