pre-amp/power amp question

[Jay_SDS]

i have a pod pro line 6 pre-amp that i am running through A 150 WATT power amp. currently i have the output of the pod pro all the way the way up ( maxed out ). i control the overall volume from the power amp. on our last 2 shows i have had to have my rig a little louder than normal and the power amp started clipping and would cut out for about 15 seconds through out the first few songs until i had to turn back down. ( to where it was really hard to hear myself and made the signal to the board weaker through the mic.
my question is .... should i have the power amp volume all the way up and control the volume from the output knob on my line 6 pre-amp

let me know what your input is on this

thanks
Jay