my headphones in my amp aren't loud enough even at max volume?

[thenastynate07]

I have a cheap 10w amp for my guitar. It has a 1/4 inch headphone jack. All my headphones are 1/8th inch so i baught an adapter, but i have to turn all volume up to max to just barely hear anything and even then its just barely. Any idea why, or what im doin wrong?