Second Build.
My active set up, for which I purchased the boards ready built, is much better than the stock passive crossover, that said, I have not been totally happy with the mid range, so its about time I looked at this. The caps fitted, 27 on each board, are mainly Polyester and the signal passes through 12 of these on each board. Polyester is not good for sound so they had to go.
Because of the number of changes involved, it was far easier just to start again, so I got a pack of 5 unpopulated PCB's from KMTech. I have replaced the 5% Polyester Caps with 1% Polystyrene's by LCR. I also replaced all of the resistors, which were of unknown origin, with PR9372 1% metal Film's by PRP. These were all supplied by HiFi Collective and can be seen assembled in the picture.
OK, so how does this effect the sound?

Initially course grainy top end with very little and I'll defined bass.
The top end smoothed out and the Bass was much fuller after about 10 hours and continued to improve after this to a lesser degree. The previous caps had focused on the top and bottom end with a slightly recessed mid range. The new caps give a much more even response across the range, with the mid range being more detailed and tonally rich than before.  I am liking what they do a lot, small details I hadn't noticed are now highlighted, little breaths, additional backing singers, those kind of details and a blacker background.

I will re-evaluate the op amp rolling now to finalise the components.