This is confusing to me. According to reviews posted online, both your preamp and your amplifier cost over $2000. Yet, the most you want to spend on a crossover seems to be $500. Placing the crossover in the system will affect the sound of the system almost, if not, more than changing out the preamp or the amplifier. Think about it. You're asking the crossover to take in the signal, split the signal, and then output the signal to its destination. For the care and expense you've taken to put together the rest of your components, it seems odd not to take the same kind of care here. Just my .02 cents...

The Marchand Electronics crossovers that Altec recommended seem to fit the rest of your system perfectly with regards to budget and the level of everything else. There's always used.