For what it is worth Zac, I always run my
amps at full gain and control my overall volume from the board.
The reason that I do this is because I find the lower frequencses sometimes get lost or are lacking if the amp is turned down.
Just keep an ear out for any distortion and keep your eye on the clip meter and you should be fine.
With your speakers being suited to your amp (ie the amp output is greater than your speakers) you will (should) hear any distortion, in which case you drop the gain a little. On the other hand, were your amp underpowered, you are more likely to damage the speakers by clipping the amp in order to drive them.
If you are unsure. Wind the amp back to begin with. I know some people who just cannot stand having the master out on their board sitting at 30%. Even though the sound is good and at the right level.