Sennheiser PX100-II

SR60 would be much more better compare with the PX100-II
comfortness, build quality i would say is really above the PX100-II

u could try search the following headphone as well :
Beyerdynamic DT231 PRO
AKG K420
denon AH-D501
Audio Technica T500, AD300
Shure SRH240, SRH440
Sennheiser HD408
Koss Portapro
definitely increase SQ 

Haven't tried one. But looking at the design I'd say it'll be a bit difficult for some to get a good fit(I know I've read some that have the problem). It is a triple driver though, and I don't think it'll be a slouch when it comes to sound quality. Some use them as a reference to test out audio rigs. Some do complain a little but that may be because it's not the sound they like or they're very very critical. I think users of Triple.Fi 10 should give a comment.

I'd say try them out. It is a rather large investment. If you can't find the opportunity to try them out, I do recommend the other cheaper options, as they fit your need for bass.

---

Added on April 18, 2011, 6:01 pm
Thinking of letting go of mine. Well in a few months though.
But it is modded and I'm not sure the warranty is still available. 

Oh, and it is compatible. it has a 6.3mm adapter. It is attached to the 3.5mm plug when shipped.
And about the sound. I find out that at times in certain music it does reveal some extra details. Details I've dismissed as being recording noise or artifacts before. They are just a tad sibilant, and bass can be felt when fed with the right music and power. Bass is quick, separation is good, though can be a bit sibilant. I've modded mine to have a slightly better bass slam and a pinch more impact, so I don't have to turn up the volume as much so the sibilance can be controlled. I've read reviews about these lower-end grados having a narrow sound stage. I was expecting the worst, but it isn't that bad really. My favourite thing about the SR60i is how it presents the electric guitar. Totally full of energy, the distortion is done very nicely, good weight. Muse's Newborn guitar entry hasn't sound so satisfying.

A recommended option for a starter headphone. 

Jaben Malaysia is a great place. In fact, try out the SR60 first, see if you like the sound. Some people don't like the Grado sound. Also test its comfort level. I'm letting go of mine because they're quite uncomfortable after a few hours. If you don't mind them to be uncomfortable, or you find them quite alright, then good for you.    They have a large array of other headphones to try out as well. You can also try out the others available.