How much does a Zobel network and its components affect the sound of speakers?


Regardless of amplification, my Merlin Audio MMI monitors have always sounded bettter using the Merlin RC Master (Zobel) Networks consisting of a Dueland capacitor and a Caddock resistor in series bringing the tweeter terminals. I've heard that some have replaced the networks using Jupiter capacitors and Vishay resistors and different wires and spades. My question is, How much do the networks and their components and associated values affect the sound? At times my speakers, while having superb resolving ability, can occasionally sound edgy, particularly noticable with voices at higher volumes.
pmboyd
As I stated, I already have the Dueland networks -- the Merlin Master RCs. Evidently some people have replaced the Dueland caps with Jupiter, however, no one has responded to my queries as yet about the difference in sound. In one instance, a chap used a Jupiter in lieu of a Hovland, but he seems incapable of articulating the improvement he notred in specific terms. 
Another possibility could be to replace the parts with cheap value matched equivalents.
Drivers vary more than can be detected with matching caps.

Additionally, ALL of the PP & PS caps I've bought and tested in past few years far exceed their tolerance spec.
@pmboyd Ahh, sorry, missed that. In my speaker (hp) crossover duelund was very superior to Jupiter. My impression across all the cap threads I've read is that that is a pretty strong consensus regardless of where people made the Jupiter-duelund comparison. Please do report back if you try. 
Finally, some recordings are not playable on systems due to Monte Carlo accumulation of faults in recording, playback electronics, cables, speakers and room.

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Wow.... what a Box-o- jumbled metaphors and kinda sorta mathematical iterative NON-SENSE!!!
 Yeah, less than desirable recording - master work, AND, YES, room acoustic interactions.
I'd strip that Zobel junk out of the system except any Zobel network inside the amplifier(s) that are there from designers mfg. all else begs problems.