My question is about bi or triamping.

Why are so many of the active crossovers I'm finding set up with 1/4 inch plugs for PA or sound reinforcement? I want to build a triamped system around dynaco tube amps for mids and highs and Adcom for bottom. Any reasonable priced active crossovers available that are flexible enough to work with quality drivers I install in self built cabinets? I loved the last system I had that was biamped using home made speakers and want to go triamped with this system.