Randy, all the EP500s have class D amps which operate by switching on and off several hundred thousand times a second, but there's nothing digital about the basic operation. "D" is simply the amplifier class that follows C.
There's no internal crossover, just a variable low pass filter. It can essentially be bypassed from interfering with the lower frequency crossover which a receiver does if the filter is set at the 150Hz max.
My diagnosis is that you'll remain upgradeitis-free if you just buy new M22s for another setup, not to replace the current ones.
