^^
Strengths: Everything above 300hz.
Weakness: Everything below 300hz.
Bass was too much for me. Boomy, bloated, flabby and it over-ran everything in the mids. This was my only complaint. Otherwise the sound is wonderful.
I don't EQ. That said, if I did... I would drop the lower frequencies by a notch or two to bring it back into tolerance.
J$ pads are said to reduce the bass bloat / impact, so they might be the only thing I'd do (if I were to own them again), but I have not heard them and so don't know if they adversely effect the overall balance. If they ONLY reduce the bass, then they would be the only mod I'd make.
My DAC1-Pre is my main source for my D7000's, but I tried everything I have with the D5000's (Outlaw RR2150, Xonar STX [as DAC / amp], iPod, Denon SACD player, Pio Elite SC-07, etc.). Nothing did as well as the DAC1, but even that couldn't tame the bass.
BTW... your english is very good.