Why my home subwoofer isn't got much power

[redox653721]

Hello,
I have a nice home system speakers and recently I bought for it a subwoofer to increase the bass.
But as I see it looks like it is not got enough power.
I have 5 speakers with a yahama htr 3063 reciver and a subwoofer which connected to a lepy amplifier which connected to the reciver also.
When I turn the volume up the sub just going crazy like it doesn't have enough power. But my Friend has the same system as mine with a different reciver and speakers but all works fine with his.
What can be the problem?

 

[redox653721]

@madmatt30 well, this subwoofer is way more then 90$ for me. If I could I would but in my country these stuff are very expensive.
I bought this sharp subwoofer from someone who used it for his car, and it sounded really good in his car.
So I'm gonna stay with that sub for now

 

[redox653721]

OK guys I guess my problem is solved, thanks for helping, I was trying to figure it out for a while..
Thanks. Appreciate your help.