Correct me if I'm wrong... those JBLs are going to draw anywhere from next to nothing all the way up to 5.2 amps, depending on how hard I'm pushing them? However, going by what I discovered with the power meter, they're "probably" going to not draw too much more than the Yorkvilles do under "MY" normal usage?
Expansion more than correction: it depends. Yeah. Mostly it depends on any difference between the Yorkies and JBLs in how much electricity it takes to make equal SPL. The reality is that about 5.6 Amperes is "Full Tilt Boogie" and it looks like that's a brick wall of some kind.
Use #12 AWG extension cords. Use the shortest length you can for each run. Don't put more than 12 Amperes of load on a 15 amp circuit; 17 Amperes loading on a 20 amp circuit. At that point you've done all you can do and you're at the mercy of the facility wiring.