Audio Systems: Bedroom Acoustics, bedroom acoustics, amp off

Question
Hi, thanks for volunteering! I'm the mom of a budding young rock star- my son Jimmy. He's 15. He just got his new giant Ibanez amp last night for Christmas. He plays the electric guitar and is into Power Metal, learning to shred, Death metal and all things loud!

This is cool with me, but I'm a single mom on a budget and we're noticing the amp sounds different in his room than it did in the store. I'm assuming this is a matter or acoustics. Can you please suggest some budget friendly ideas we can do in his bedroom so he can jam? The room is about 15ft by 12ft. There's a windo on one wall, a door on one wall, and a closet on one wall. He has stuff hanging all over the walls. We noticed the sound is better when he put on the casters to get the amp off the carpet. Any suggestions on what we can do to the room would be appreciated!!
Thanks,
Lisa
Jacksonville, FL

Answer
well the cheapest thing you can do is move it around and see how it sounds in different places.  
You already found how the casters help.
It may help me alot to know what seems to be lacking although that's a tough answer for you to give.  
Is it lacking deeper bass reagons or tonal balance or doesnt seem loud enough or just not a natural sound or what?  does it have settings on it or better yet exactly what model is it, I can look it up.

Thanks.