I'm starting to read some of the recent posts and see that many of my comments have already been covered to one degree or another. For example, the link between Steen Duelund and Harvey Rosenberg, the Fisher EL84 amp, and so on. I was also going to comment that larger caps sound better, but that's been mentioned, too.
A few more random notes:
You're right about the cheap parts in most speaker x-overs. However, keep in mind that most x-overs have too many parts to begin with, so it's no wonder that cheaper parts are common. Commercial products are built to a price point and that's always been a problem for the audio perfectionist.
Regarding your EL84 amp, I'm not sure exactly what was done or who did it, but we spent a long time (years) mixing and matching different parts, including tubes, caps, and resistors, before hitting on the magic combination. Regardless of what we personally liked, to get the sound you love requires going through this type of round-robin on your own while listening in your own system. In order to understand how different parts affect the sound, I always caution people against making permanent changes without doing a personal comparison first.
As the amps and other components in our system became more refined, we went through these comparisons at least three times for every component. We typically made only one change at a time, which is why it took about eight years to feel that everything was fundamentally right. That was two years ago and we're still making improvements, mainly in the front end.
Also, running pentodes as triodes doesn't really change the sound that much, it mainly reduces the power. If you want a true triode sound, then it's best to use a true triode amp. When properly implemented, the EL84 is still the best of the pentodes and a good, musical performer. It will benefit from a tube rectifier, however, such as the 5AR4/GZ34. I recently bought an Olson Classic 40 amp (GZ34 + EL84's) for $200 and even with the crappy mods that the previous owner did, it still sounds musical.