I guess the issue isn't so much that I'm "looking" for bass as it is that when I am mastering the shows I record the Sony's - IMO -- give a poor reflection of the bass in my recording. On the headphones the bass will sound nonexistant but yet when I crank it up on the home system or hell even in the car it sounds much richer, fuller. hard to mix my shows when I'm dealing with that...
This is exactly the issue I had with the 7506 cans, so I dumped them. After doing some research, decided that the Grado SR225 seemed like they were supposed to be good cans, so I got those. I found them very nice to listen to, but not for mastering.
I had the same feeling with the Grados as with the 7506 -- couldn't really hear the low end, so I didn't know if mastered a recording with way too much bass or too little. I chalked it up to: mastering just doesn't work on phones, so use a speaker-based playback.
After all the fluffing of the Audio-Technica ATH-M50, I got a pair of those. Whoa, what a difference! I finally feel like I can master on headphones. I still prefer speaker-based mastering, and always check the mix back on speakers before committing, but I can at least approach the mastering task with the M50's. The M50's do have some bloat in the 100-200hz range I hear, but I can get used to that and master around it (and have some bass bloat below that, but I don't notice that as much).
Not to say they are the only phone that works for mastering, but far better than the 7506's and SR225's I've owned. And I wouldn't necessarily say they are a better set of cans for general listening. In many ways I like listening on the SR225's for typical headphone playback. I don't use phones too much though for general listening lately.
Here's the frequency graph of the 7506, SR225, and ATH-M50: