Best three way cross over?

Big question! It sounds like it might be a perfect time to consider actively bi-amping your speakers. Using the active x-over between the bass and mids, would eliminate that part of you x-over causing problems. (By the way, you didn't mention your speaker model.)
The best electronic x-over (in many peoples opinion) is the Krell KBX. Krell will make a custom board for almost any speaker for $200. There are KBX's for sale on this site and on ebay, right now.
Also, I recently changed from passive to active x-over using the KBX.........the single biggest improvement that I have ever made to my system.
Richard

This site http://www.sound.au.com/ has a very lengthy article on the merits of biamping/triamping loudspeakers using active crossovers. It also has a project on designing a very nice phase coherent 4th order linkwitz riley crossover. Marchandelec.com also has many electronic crossover kits. Once you opt of electronic equalization you'll need to adjust the gains on your individual amplifiers to smooth out the frequency response since your three drivers probably don't have the same efficiencies/sensitivities, and the passive network was designed to attenuate this. There was another thread here just a few days ago asking about electronic crossovers too--it might have some info to help. The electronic if done right will probably increase the performance. You won't lose power in the passive network-in many cases the equivalent of halving the amplifiers power, and intermodulation distortion can be reduced. Passive crossovers in three-way systems can become unpredictable at higher output levels because the temperature of the voice coil changes and therefore so does its electrical characteristics. It would help to state what speakers you have--PSB or Avalon Eidolons? Another thing is that the quality of parts in your passive network could possibly be better. With seperate amps you'll make full use of there effective damping to a given driver. But do contact the manufacturer of your speakers to find out just what they've done with the crossover--sometimes the crossover can be used to smooth the frequency response of the system even in a single drivers operating range--not just the crossover region, which may complicate things. I've been toying with biamping myself, but in the case of two way designs I'm still uncertain if its worth it. However, with a three way it many cases it is.

There may be a simple solution to your problem. Some speaker drivers improve dramaticaly with the implementation of a zobel network across the driver . Both my friends Dunlavys and Pipedream speakers were improved with zobels placed across their drivers. The Dunlavy's Bass driver in particular sounded "muddy" before a zobel was used (we didn't realize it was "muddy" until AFTER we did the zobel, boy were we shocked at how much it improved!). It is extremely unfortunate that many speaker manufacturers don't implement (or understand) how beneficial these circuits can be. In many cases a Zobel makes perfect electrical sense in improving the drivers control by the amplifer, and can do wonders for even the most highly regarded "recommended" speakers. It amazes me that so many audiophiles think that these speakers' designs cannot be improved upon. You may also see contradictory responses to my zobel recomendation that state things like: "but zobels have issues such as their power robbing ability". Unfortunately, this is not the case, and just misinformed audiogon speaker tweakers, who don't really understand what a zobel does, or how these circuits are almost always a "win-win" scenario when they are implementated correctly.

Ehider, in response to the zobels, are they ever used when a speaker is being driven with an electric crossover? And more specifically what do they do to improve performance? I've only seen them used with high capacitance speaker cables like Goertz to keep unstable amplifiers from oscillating (If memory serves). I'm just curious/asking since I don't now all that much about them. Its just that the disappointing aspect of passive networks is that the only way to smooth the frequency response of two drivers of different sensitivities (not uncommon) is to knock the more efficient driver down to that of the least efficient driver (unless you're sticking a horn on one the less efficient ones, not common). So technically using electronic equalization will allow the driver to perform at its full sensitivity and make the most effective use of the amplifiers power. A not uncommon padding of 3 db on a driver is the equvalent of needing an amplifier twice the power to reach the sound pressure level (compared to an active design all things being equal of sorts). I'm just dwelling on it now; I get a little teary-eyed sometimes when I see a 95db efficient driver built into a system that only carries a 90db system sensitivities--5 db just thrown away :( No, watts aren't that expensive (although they can be if you want them too) but.....if you have your heart set on some little 10watt class A amp 5 db's alot.