I'm considering 1 2-channel amp. Both channels 450W RMS @ 2 Ohm.
1st channel for both speakers (each 150W RMS @ 4 Ohm) wired parallel to get them to 2 Ohm. So that both receive 225W RMS.
2nd channel for the 300W RMS @ 2 Ohm subwoofer.
That should work perfectly, considering amp "should" be 50%...