Hi Marc, Well, I can at least speak to the RS1B.... On the top end, we found that carefully matching the sensitivity of parts and fixing their output rather than using the pots was noticeable improvement. We never really changed the design, but a few key parts changes also made a difference. No doubt, they were well thought out...Not sure about beyond reproach. I'd rather listen to them matched with a good electronic crossover and amp any day. No comparison. If anyone truly multi amped these speakers with quality product, then take the time to properly adjust them out, t I would be surprised if you liked the passive crossovers better.