Looking for an economical upgrade for the mains in my JBL NSP1 II setup. I know they are discontinued but was thinking about a pair of N28 II's, will these blend well with my N24 surrounds and N Center? Are there significant differences between the N28 and N28 II? Are there any of the E Series I should consider? Does anyone have a reliable/economical source for the N28's or other JBL speakers? Thanks for any/all advice.