Say you had a 2 way speaker without a passive crossover. Each driver is hooked directly to each channel of an XLS Drivecore amp. The internal 'Pureband' active crossover (LR4) would be set according to the driver specs, and the drivers' output levels would be matched via the channel gain knobs on the amp to make a fairly flat FR (?). Audyssey would take care of baffle step compensation (?). Voila: active speaker!
That is real active bi-amping. It doesn't matter that both amps happen to be in the same box.
But this is a noob DIY misadventure. Good speakers have more complicated crossovers. You can't just pick a frequency and run high and low pass filters at that frequency and get good sound, generally. That's why you don't see anyone using pre-fab passive crossovers for their DIY speakers. Audyssey doesn't do enough to make up for baffle step, etc.
What you can do is hookup a minidsp to the amp and run active. Until I built a passive crossover for my seos-15/td-15m center, I was doing just that with an xls-1500. I was using dsp settings that bwaslo developed for the drivers that I was using. Or get a behringer inuke DSP amp and use the internal DSP.
Does the Crown XLS series have built in EQ and DSP functions? I came across an XLS-202 and an XLS-1000 but I am not for sure if they would be good for driving, EQ'ing, and handling the DSP functions for a front LCR?