I'm not doing anywhere near 24 zones, but I'll likely be using the Triad AMS-8 paired with 1-2 Episode/SnapAV 12 channel amps (70W x 12ch). The Triad just seems to be the easiest "plug and play" solution at this point. If you are looking for the easiest/cheapest solution, I would consider getting an AMS24 and using the three amps that you already have. If you are looking for new amps, the Episode amps can be found for a decent price and they are fully featured (with triggers, bus input/outputs, etc).