I see this a lot in xovers. They would use an inexpensive (Solen or Axon) cap with an expensive film and foil bypass cap (Audiocap or Hovland). I understand the economics of it being that it saves lots of $ over using just a single large value film & foil cap. But what else? I've got a good idea & understanding but want to be sure. I take it that it is not something you can figure out with X*Over 3 pro and a Clio system. It is more of a listening exercise, done with a trained ear. From what I can gather, expensive bypass cap adds a little something to the xover for a better sound or to achieve more of a certain tonal balance and improve the effective high frequency performance (since this is done more on tweeters than with mids or woofers). Basically a standard metallized cap wouldn't sound as good. That's what I could figure out but please LMK what else there is to know about them.