I did not like the polypropylene Obbligato oil caps used in rebuilding my AA networks. After years of my K-horns sitting, I decided to try again, with a pair of Type B which I rewired
as Type A in charged coupled configuration - this was much more to my taste, better detail, less fatigue - ESR on these old caps was fine. I first heard MBGO years ago in a Baltek90 speaker and was impressed. They may even be better than KBG (?) - they're less expensive and more compact. I think I'll get more for my Karlson projects. Of course subjective synergy
may occur with different caps for different crossovers/drivers/amps/DAC, etc. My Heresy I are stock other than KBG caps (not charge coupled) and have beautiful midrange with an an inexpensive singled ended ultra-linear EL34 amplifier.