How good is the crossover in your loudspeakers?

Electrolytics don't belong in any crossover, virtually any film cap will better electrolytic, and deterioration won't be an issue. 

I don't know if timbre has been raised as an issue, my sole issue with active crossovers is they would necessarily alter timbre. I've chosen specific components and modified parts within some components in order to achieve a pleasing timbre.   I exclusively run SET amps and SET pre, no way do I want to introduce a SS active crossover to this.

Number of considerations. System and room speaker being used in, the exact same speaker can have many voices. Changes such that freq response, phasing, impedance affected may or may not be a good thing. In the process of designing/voicing loudspeakers manufacturers limited in matching with equipment, rooms, and then we have designer or listening panel preferences. You better know exactly what defects you hear and the proper 'fix' for those defects before messing with crossover values. Replacing individual components such as capacitors, resistors, inductors with same values as original good way to go while mitigating the risks of changing design parameters.

I believe Danny will substitute an individual's choice of caps for the Sonicaps, recently saw one of his videos with Duelund CAST caps loaded on crossover.  Physical space limitations are generally the greatest issue with using the best of best film caps, Sonicaps much smaller footprint, this, as well as cost likely the reason they seem to be de facto replacement cap.

As pertains to the desirability of attaining flat freq. response the videos @lalitk  refers to are informative. So, guy designs his speakers to measure exactly to his liking, result is nothing close to flat freq. response, the chances that others will find pleasant sound quality with these  in great doubt. While subjectivity certainly plays a role in speaker design, one needs to start with good objective engineering. Flat freq. response, proper phase, impedance curves, etc. Dannie finds fault with subjectively designed speakers, applies objectively determined optimizations. I presume some like their subjectively designed speakers since their preferences align  exactly with designer. Still, for most, having properly engineered speakers should be foundational, you can tune to your heart's delight with sympathetic component matching, room treatments, etc.

I'm with @texbychoice To believe all this equipment, software doesn't impact sound quality is illusory. I've assembled an entire system with a particular voicing I prefer, I don't want timbre, tonality touched. This includes my passive crossovers intentionally voiced with purposely chosen crossover topology, caps, inductors, wiring, drivers, all work harmoniously to provide preferred voicing. Speakers 103db sensitivity, 7 or 8 watt 300B monoblocks provide an excess of power, so much for passive crossovers sucking power.

As for an all analog system, why in the world would one want to add DSP, defeats the whole purpose of keeping a vinyl setup with it's unique sound qualities.

It's generally acknowledged speakers are the greatest variable in an audio system, therefore, has the greatest influence on system sound quality. That being the case, it makes sense optimizing one's speaker would provide major dividends. Assuming OEM has optimized speaker using relatively crap crossover parts is plain wrongheaded. For manufacturers, cost may be one deterrent to using better parts, but ignorance likely contributing factor. Also, should we assume OEM's have golden ears?

@carlsbad2 I'd estimate benefit of my crossover mods far exceed the 2% you mentioned, the inductor changes alone provided that. As for determining benefit ratio I'd posit the low parts count from running SET pre and amp contribute to a relatively high benefit ratio for my crossover mods. I can easily hear changes with swapping out coupling caps, resistors, tubes in both components.

For the doubters, empirical evidence should be your gold standard, don't rely on others for your evidence.

The VH Audio V-Cap ODAM are an oil damped advanced metalized caps, reportedly very nice in crossovers, and everywhere else for that matter,  and relatively smaller physical size. Available up to 47uf. It is crazy to see the large value electrolytics used in some crossovers. If they only in for woofer use, I'd still replace mid and tweeter caps if possible.

Another nice mod I've found is the Duelund bypass caps, specifically made for use in speaker crossovers, I use the silver as a bypass on a Jupiter VT, balances out the warmth of VT with the openness of silver. You'll see the Duelund bypass caps raising ratings of most any cap by a couple numbers in the cap shootouts. 

And this brings me to another advantage of passive vs. active crossovers. Myself and others are intentionally manipulating voicing to get exactly the sound quality we seek. An active crossover may give me exactly the freq response I want, but doesn't offer flexible voicing, timbre important here, this not just about tonality. Also, a class D or A/B SS active crossover is the last thing I want to add to my SET tube system. I'd much rather use DSP software such as HQPlayer to tweak my sound, much less obtrusive on the voicing. 

I haven't watched Danny's videos religiously so I don't know what he's left out. In any case one shouldn't rely on only one source for their information. Sometimes I forget others far newer to high end audio, I've learned from so many sources over the decades.

As it pertains to speaker mods, so much more goes into the final result such that a one solution mod or speaker not possible. One should realize another person's modifications may not work in their system, room, or be sympathetic with their perception of sound qualities.

Modifying audio components in general allows one to obtain exactly the results one desires, this presumes one knows exactly what they're seeking. Understanding how to achieve those results requires either the assistance of others who have specific knowledge and/or much experimentation. In the case of my Klipschorns there has been much knowledge accumulated over many decades, I relied on others for a pathway and then applied my own unique mods, result is I finally have my end game speaker.

My perspective on active vs passive, active is a science, passive is an art. Mods have always been about art for me, I rely on others to provide me with the science, my unique mods conform with good science. Passive mods is art in the sense one can find the perfect recipe via various combinations of high end caps, resistors, inductors, each which may have unique sonic qualities. 

Danny provides both a general understanding and/or model specific guideline for speaker modifications. Funny how some think this is a disservice when in fact he's handing out research and knowledge free of charge, he's not requiring one to make purchase.