The fatiqueing sound from your La Scalas might or might not be due to the new caps. If you have a tuner or can put an old CD on continous play, I'd do that, turn the volume down and walk away from the system for a few days and listen again. Here's another thread on La Scala crossover upgrades:
http://www.audioasylum.com/forums/hug/messages/2/25576.html
http://www.audioasylum.com/forums/hug/messages/2/25576.html