Not to beat an old thread, but I stumbled upon this thread after searching for upper bass. There's a short story about that relevant to to my question, so I'll tell it. My audio journey has been a relatively short 5 years, and in that time, I can't say I've come very far. Although, I have finally been able to identify precisely what I want in headphones, and it's not entirely bass, my adoration of the DT770 showed that to me. I'll keep this short, the first entry level headphones I got were the Shure SRH440, and I liked them, with the exception of their non-existent bass (to my ears, many people found them to be fine). I then went to the opposite side of the spectrum, and got the XB700, and I liked them, with the exception of their simply poor sound quality. Then I bought the DT770 Pre 32 ohm, the ATH-A700, and later the HFI-580. I didn't like the A700 for anything really. The HFI580 sounds nice on its own, although its sound in the mid midrange sounds unnatural to me. I then tried to think of the the HFI580 stacked up the DT770 32ohm (since I had returned them at the time), and I thought that they were roughly equal with the DT770 32 ohm edging ahead a bit. Then, I got the DT770 Pre 600 Ohm (after getting the ASUS Xonar Essence STX, which do a great job amping them. I can't get past the 2 o'clock mark on my quietest song). The memories of the DT770 32 ohm flooded back to me, including my initial disappointment with their SQ. After some burn in (and I know that they're not close to done), the DT770 600 Ohms have already replaced my HFI580. I can't actually go back to listening to the HFI580 because of how inadequate they sound in comparison, However, I must take issue with the DT770 600 Ohm's lack of upper bass/lower midrange. Comparing the FR of the DT770 32 Ohm to the 600 Ohm, the 32 Ohm does give more in this range. However, I haven't replaced the DT770 600 Ohm with the 32 ohm because of how powerful the upper midrange and treble is. It's painful to my ears, to be honest. 7 kHz-20 kHz has been cut by 19 dB, and 1.8k-4k has been cut by -14 dB, it probably drastically alters the characteric of these headphones, but honestly, any less and it's painful. I recall this issue being drastically improved over burn-in with the DT770 32 ohm, but I'm not sure if the same will happen for the 600 ohm version. On the plus side, I like the way they sound with this alteration (and appropriate EQ'ing the other frequencies to compensate). I really like the upper bass/lower midrange of the DT770 line, with the 32 ohm version doing the best job, I think. However, I feel like I could also go for more natural sounding and detailed HFI-580 with better representation in these frequencies.
So my question, to whoever can answer it, should I upgrade to the PRO-900, switch over to the Beyerdyanmic DT770 Pre 32 Ohm, or take a look at the Shure SRH840/940 or the Denon AH-D5000? Through my journey, I have found that what I really love is strong bass (XB700) with an impressive and liquid upper bass/lower midrange (DT770) with great detail across the rest of the spectrum (DT770 and Shure SRH440).