I do have a pair of JBL LX500's and I like them very much.
There are two versions of this speakers. Are yours floorstanders?
Mine are made in Denmark and are 4 Ohms. It's said that these are much better than the 8 Ohm version, made in the US.
I wouldn't know because I just own these (bought them second hand) and haven't heard the the 8 Ohm version.
But, for me, these are just fine.
Mind you, they improved a lot after I put some spikes on them and put each on 2 pavement tiles with 4 washing machine dampers between the tiles.
It was needed because they sounded a bit muddy without them on my wooden floor with carpet on it.
I wouldn't be surprised if yours are also made in Denmark since we both live in The Netherlands (we met in Terneuzen).
Matthieu