I have really no knowledge of the AKG you have, but this is what I pulled from joker's portable can review:
Head-to-head comparisons with the K81DJ are inevitable but I will try to be as general as I can. In a nutshell, the K181s alleviate a lot of the issues I had with the sound of the K81s but just don’t go quite far enough. They are more balanced and less dark than the K81s. The low end is still very powerful but the K181s do a better job of controlling it and it is even more extended than with the K81s. The bass also feels like its integrated better into the overall sound. Additionally, there is a bass toggle switch, but after playing with it for a bit I decided that it is better kept in the “low” position for fear of altering plate tectonics. The midrange is very clear and boasts a good amount of detail and very natural tonality. It seems slightly forward compared to the K81s but this is likely the result of the K181s’ better bass and treble control. The treble is equally natural and very smooth. Though it lacks the distinctive sparkle of the K81, there is not a hint of harshness or sibilance with the K181. Amplification has an effect on the K181s, but not so much that I would recommend getting an amp just for them. I have also been using them with a DHC Cryo K702 cable, which sounds brilliant with these. It really helps with the treble rolloff issue that these share with the K81s. Overall the K181s are still far from being flat, neutral monitoring phones but they can be quite fun, especially with the club-type music for which they were so obviously designed.
Since you like the bass end turned up, I think you need a bassy can which the Sennheiser is not. The HD558 is a great can, but you may find it lacking in bass. Also they are open, which means that the back of the headphone cup is a metal grill which allows air (and sound) to pass in and out freely. This means that if you turned on the Sennheisers and put them on you leg like you said with the AKGs, they will be at least as loud, but probably much louder. Open cans have lots of benefits, but isolation and leakage is not one of them.
Like I said before, the Beyer DT770 should work well depending on how loud you listen. I had the 250ohm and ran in straight from my computer before I finally got an amp, so I know it can be done. There is the 80ohm version though which would be even easier to drive.
I definitely like the design of the dt770s, but there were multiple reviews on amazon saying hey wouldn't be ideal to use without an amp, and that was the reviews of the 80 ohm one.
What would you say about the new Sony XB800s? Or the audio technica ath-m50?
And the more I use my current headphones, the more I need new ones based on comfort alone. It has a lot of bass and that is nice, but comfort is top priority. And if too much bass can lead to discomfort, then I will just need to accept that I won't get as much bass, but also won't feel any pain after using them for a longer period of time.
Edited by strausd - 10/6/12 at 10:31am