Never go by max wattage, those numbers are inflated especially if you don't list the correct ohm rating on each channel to acheive that wattage. You should only every talk about RMS wattage. THat's the more commonized number to refer to.
It also doesn't matter how many watts your amp is. Just put a multimeter(oscilloscope is better), play a sine wave pattern on your stereo at a steady frequency, and put a true-rms mutlimeter on your amp, set it to AC voltage reading. Then adjust your volume on the head unit to your max listening volume and adjust your gain to match the maximum rms wattage of your subwoofer. So if your sub is say 100watts rms and it's wired for 4 ohms on that channel, then using basic ohms law, V = sqrt(PR). So sqrt(1004) = 20Vrms. So you want to adjust your gain to 20volts on your multimeter. You can download amplifier adjustment test tones on the internet. As long as you adjust your amp like this, you can run it all day long and never blow your subwoofer, your amp could put out 10,000 max watts and it wouldn't matter.
Also, you can explore wiring options for your amp. Most 2 channels amps are bridgeable at 2 ohms. If your subs are 4 ohms each, you can wire them in parallel to make a 2 ohm effective load and get the most wattage out of you amp. If you wire each channel separately at 4 ohms, your amp might not even put out the wattage to max out the subwoofers.