I have a pair of AKG K240 headphones. I like the type that go over your ears. My amp is a NAD with 70 WPC. I listen to rock, everything from Jimi to Pantera, Arch enemy and everything in between. So I listen to these a little loud and they sound stressed for lack of a better word. Just like an amp needs headroom I feel that there is no headroom left in these headphones at my listening levels. Anyhow my budget right now is $150.00. Any sugestions would be appreciated. Would going to a closed back inprove the sound/volume?