K702 has it's peak around 2.2khz while HD600 has it's peak around 3.7khz and they almost invert each other at 6k but yeah the bass is the same... they're both neutral on that end :)
I just find it really interesting how close HE-6 is to HD600's treble on the graphs. That peak at around 14khz is perfectly alligned to the same frequency as is the 22khz peak. It's a really close match... I feel intrigued in checking the HE-6 out.