I'm another who had Danny do testing and build a crossover for my 1990s Epos ES12 speakers. He's been a respected designer and engineer for the industry for years on years, so he has a great deal of "insider" experience and prefers to do his own thing. With "audiophile" speakers, many comment and worry about losing that speakers signature sound with messing with a crossover, thinking that you buy and love the speaker for the sound it made, so what could possibly be wrong with it? I was VERY concerned about this, thinking "no no, but this was SUPPOSE to sound this way". Well, yes, it was....but that doesn't mean it is 'right'.
As most likely know, the Epos line from the original ES14, 11 and 12s were well known for amazing crisp detail and accuracy, strong central focus, a bit lean, but very "British" sounding. Some of this partly owned to the actual LACK of any crossover other than a filter cap on the tweeter.
Danny uses the same industry testing methods I believe every single manufacturer uses to test speaker designs, box designs, and crossover networks. The testing proved that there were irregularities in the signal response, enough so that what he was seeing on a response I was hearing from the speakers. Some, were part of the known/loved "Epos sound" but over time were annoying and just not pleasing to me.
The crossover components, his time, testing, and time with me on the phone and emails were all worth past the $300+ dollars (high quality components, schematic, no rez, wires and silver solder). I love these speakers so much already, despite the age (a lot for sentimental value). Once the new crossovers were put into play and broken in (took awhile), I love these speakers even more. I was worried that I would lose/miss the "Epos" sound, but in truth what I was getting were bumps and dips in certain frequencies that created some of that "signature sound". Once properly controlled with a crossover, the design and box really worked incredibly well together: still has crisp accurate detail, still great focus, but with a better blend across the frequency response, more richness, and (ugh) more 'musical'.
I am able to test the speakers against themselves without the crossovers (I have a second pair left as/is), and it is dramatic how basically it sounds like someone screwed around with an EQ, and I need to rely more on the Rega Sub to 'fill in' with the original crossover-less version. I lost nothing, but gained a great deal. They still sound like Epos, only smoother, same detail, a bit more punch (relative term for a speaker with a 5" driver) but a much better listening at all levels, for long periods of time.
What I think is most interesting is the flack GR/Danny takes from both sides of the audiophile community. He is an actual designer and engineer, musician, with decades of professional experience, and he is a bit of an audiophile. He gets flack for building crossovers or criticizing speakers with comments like "but did you even listen to them?! That's how they are suppose to sound!", to criticized by the engineering community for pushing 'snake oil' (seriously can we please retire this hackneyed term already?). He can go from being attacked for only looking at measurements, to NOT looking or depending on measurements for things like speaker cable or power cords. Just amazing.