Are there any audible differences between the EX51 and EX71?

I bought a pair of the EX51s a couple of days ago and REALLY didn't like them, especially for the price. I returned them the same day. They looked almost identical, and the specifications are identical and they both use 9mm drivers. I'm assuming they are the same headphones as the EX71, except without all the extra "stuff."

The EX51 were shrill compared to my Koss Porta Pro Jr and the headphones that came off of my RioVolt SP250 Mp3/CD player. (BTW, do you know who makes those headphones for the Rio SP250?)

Anyway, i'm not expecting any earbud to sound like the Koss Porta Pro Jr, but i've heard some good ones that came close. The headphones from Rio are REALLY good in my opinion. They fit like the Apple headphones, so they're not all that comforable, but its okay. The bass is excellent and the highs and mids are adequetly balanced, not too bright, and not muddy at all. Not perfect either, but they are better than most other headphones i've tried.

The EX51, like i said was shrill. The bass output wasn't anything like some of you have described...there almost wasn't any, even with different placements and earpieces. The low-mids were lacking, but punchy at best, and the highs were overpowering a bit. Not too bad for an earbud, i must say, but for 40 dollars...i was expecting a bit more out of it. They were a WHOLE LOT better than the Koss earbuds though. Also, they weren't as loud as the Apple earphones or my RioVolt headphones, but it was still acceptable considering the isolation.

I LIKE the isolation. I thought i would hate very isolating headphones, but i could really see their benefits in some situations. They were ultra comfortable too. If the EX51 had a touch more bass, and a touch more mid and control, i would have kept them. They felt like pillows for my ears. :) The largest earpiece really improved the sound and fit for me...man were they comfortable.

Anyway...my question was: Is there a difference between the EX51 and the EX71? If there are any sonic differences, then maybe i would spend the extra 10 dollars to test them out.

P.S. As tempting as the Shure E2c sounds, i've just decided that 79 dollars is way too much for me. If the EX51 is anything like the EX71, then i can't see myself owning something with LESS bass output.

If i want SQ, and bit of comfort, i would get the Koss KSC35. I haven't tried them, but they look like they use the same exact drivers as the Koss Porta Pro Jr...and i LOVE those. I've tried clip-on headphones before, and they were ok by me. Someone also meantioned a new Senheisser PS60 headphone. It goes around the neck...those are comfy too for excercising and activity. Haven't tried those either...but i've heard nothing but good things about Sens..