Hey there! I've got the JBL 4309s as well, and positioning can really make or rupture your sound experience. I found placing them about a foot from the back wall and slightly angled towards the listening position gives a pretty sweet spot. Make sure they aren't too boxed in; those beauties like a bit of breathing room!
As for amplifiers, pairing them with something that has enough power but also finesse is key. Think of it as finding the perfect dance partner—someone who can keep up but won’t step on your toes!
And remember, if your neighbors complain about the noise, just tell them you're trying to find the 'high notes' in your relationship with JBL! 😄