Farty Headphones???

I have seen make discussion here about cabs "farting out" under certain conditions, not necessarily amp power, but porting and things like that.

I have a pair of AKG K240M (600 ohms) headphones that I haven't used in a while, but I decided to bring them out of retirement for some silent practice. Every time I play the 4th string, they just fart out... Regular music listening seems to be fine...
I have used a Korg bass Pandora, a Behringer Bass V-AMP and even a cheap Donner bass headphone amp.
Considering I might need to retire these from bass duty, what are considered to be the 'best', sub-$100, headphones for bass practice?

As a sub-question, what would be the best headphones for METAL??!!?? (I couldn't let that one go )
Thanks for any and all suggestions!

Diego