^ I know exactly what you're talking about, this is the burning question for me if I will like the headphones or not and might be ready to admit I will sell these based on initial listen even. It seems to have to do mostly with how the soundstage is projected, some are very engaging a bit more in-your-face, you're in the middle of the music with everything surrounding you while others it may feel you're in a concert hall listening with a more relaxed sound that is not as engaging as in you don't get the feeling you want to dance to the music etc.
Sounds like M-Audio Q40 would be a good option. It has strong but GOOD quality bass that also improves quite a lot with amping. I'm still amazed how great this headphone handles bass from bass quantity vs quality point of view, Beyer DT770 Pro/80 and M50 are no match even, the Q40 has both stronger and better quality bass. The bass also extends very nicely and sounds even in the whole range and it definitely packs a lot impact in the whole range, very punchy, textured and controlled bass, those 3 words explain the bass response of these headphones perfectly.
Besides the bass the mids and highs sound neutral and very even in the whole range, there's a tiny boost around 8kHz or so which gives the highs some sparkle but I'm sensitive to sibilance and extended highs and these are just right for me, they are on the border of becoming too bright to me as I prefer neutral highs but these aren't TOO bright especially after I stuffed some paper beneath the pads to make them deeper which also tamed down the 8kHz peak just a very tiny bit as well as possibly improving the soundstage somewhat as there's more space between the ear and the drivers while still keeping the engaging sound.
On the cheap Panasonic HTF600 fits the description perfectly as well which may cost like £30 but to me performs like 3x the price sound quality wise. Compared to Q40 it's like a more "fun"/engaging headphone in favor for less detail, it's warmer and "easier" to listen to as you forget about analyzing the music and just wanna dance along with it but if you also want more detail then Q40 is it while still being fun. You can get both for £130, I suggest picking up them both. If you want another cheaper option, Brainwavz HM3 is suprisingly good for the price and fits under the bit more bassheavy & fun description and has really nice design.