Hi Of course there is a bunch of projects on the net , but I never tried to build any of . I tried some old single-end design but there were a lot of dynamics issues and collorations. So, my question is do you know some accurate and "high end " design? Maybe some discrete design?
Designing an accurate "active" crossover begs the question "accurate" to meet what target response? Stand-alone active crossovers generally aim for steep symmetrical band pass filters that don't interact too severely in the crossover regions between adjacent outputs. Passive crossovers, are a huge tradeoff in trying to steer the right frequency ranges to the right drivers with minimal losses, good driver protection, and again good combining in transition regions.
Designing a dedicated active crossover for a known loudspeaker, means you can design a filter set from scratch that much better matches what the specific drivers want to receive. Ideally you want to look at the strengths and weaknesses of each driver. The performance of the drivers will often lead you in a one direction, or another. Say you are crossing over between two drivers where one is still pretty flat, but the other is already in trouble (phase shift and roll-off). For this situation you want a steeper slope on the marginal driver to keep it out of trouble and rely upon the stronger driver to pick up the slack. This suggests an asymmetrical filter topology like the "derived" or subtractive filter topology. One conventional multiple pole HPF or LPF, is subtracted from unity to create the adjacent driver output. This derived output will not have as steep of a slope as the convention filter, but the nice thing about this approach is because the signal is derived , it will recombine to unity (most crossovers filters don't). The stronger driver can tolerate the more gradual slope, and it uses less parts with no need to precision match the two filters.
In general for loudspeaker crossovers, less phase shift is better, so the best sounding in that regard is 1 pole. But obviously the one pole filter has the slowest roll-off. Again here is where you need to look at the drivers and see how quickly you need to roll off between drivers to protect and serve. Most passive crossovers are lucky to generate 2 pole crossover responses.
It would be instructive to reverse engineer the passive crossover to understand the approach the original speaker design engineer chose.
Sorry about the non-answer answer, but IMO the question is not which high performance circuitry to use, but what filter curves to target.