The R-A60F is 4 x 150W Max. Your speakers are only 45W.
1. Don't turn the volume up too high. (best option)
2. Buy new speakers.
3. Get a smaller amp.
But it also depends on your speakers set up and impedance.
2Ω - 16Ω will significantly change the amps output.
Series or parallel wired speakers will also significantly change the output.
Martin