To drive your two Dayton subs, I would suggest the Crown XLS 1502 Drive Core power amp. At 575 watt/ch with a 4 ohm load, it is powerful enough for your drivers. The Crown line is a very reliable product and more solidly built than the Behringer.
Your subs will handle a short peak power up to 800 watts. The recommended Crown would be suitable for them. I notice that you might replace them with 18" subs in the future. You might prefer the XLS 2002 for the bigger drivers, but this one consumes more power, and it might require a dedicated 20 amp circuit depending on the size of your listening room, your listening distance and desired maximum loudness. But don't ignore the fragility of your ears when they are exposed to high SPL.
DriveCore™ 2 Series power amplifier — 300W x 2 at 8 ohms, 1,550W x 1 at 4 ohms bridged
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