I have an Pioneer SC 35 with a 250 watt amp and I run all speakers as small. This increase headroom for the system. XO your speaker at 100 Hz will also increase your headroom. Do these things and you should be fine. Rarely are all five speakers working at any one time and like the one poster said, most of the time you are in the single digits as far as watts. I do this for good bass management even though I have a large Klipsch RF 7 system.
Klipsch RF 7 based HT 7.4, Pioneer SC 35, Acurus Five 200 amp, Chase SS 18.2(2), VS 18.1(2), Samsung BDP F 7500, Asus/My Book Live HPC 4 TB
Yaquin VK 2100 amp, McIntosh XR 5 speakers, Samsung BDP F 7500