I bought JBL 4435 . I read a lot about the sound of them, many sound studios got them as main speakers. Speakers sound very sharp, not well detailed, not spacy , typical JBL bass response (not very deep). I looked at the internal parts. Cheapest cables, typical JBL yellow cheap caps, extreame current loss on the BI wire / single wire switch. I decided to change the capacitors , PCB board and add by the way the charged coupled concept. Cables where replaced by audioquest type 4 speaker wire (copper, rather warm soundet against original cables) I used Miflex caps couse i like them , there are mid sweet , maybe a bit layed back then Mundorf or Jansen, but are made in Poland and not in China. Check here for capacitors test on Humble Home Made Hifi
Crossover Tuning JBL 250TI L250
JBL 250 Frequenzweiche mit neuen Elkos , Wiederstände , Verkabelung , umgebaut auf Bi-Wire Bi-Amping . Jantzen Verkabelung und Stecker, Wiederstände von Mundorf und Jantzen, Jantzen Verkabelung. JBL 250 crossover modification . All caps , cables ,resistors have been replaced. Also JBL are now Bi-Amping Bi-Wire capable.