ID series volume question

[ja3k3l]

Hey guys!
I own a blackstar id 60h, and I LOVE it! It has the best tones around and is suuuuper flexible. The only thing I have realized is that the volume knob seems to not do too much after the 12 oclock point. Granted, it still gets pretty loud, however I believe that the volume is linear, which means that it isn't living up to 60w. I run my pod hd500x through the fx loop (4cm), however, this doesn't seem to be the problem.

My question is: Is the volume knob linear? And if so, is there any way I can make louder?