I'm a bassplayer and love the K701. The difference between the 701 and the Quincy Jones 702 is mechanical. The 702 has a kind of bass reflex opening. You could even mod the 701 to the 702.
The K701 have true low end but they don't try to kind of make up for the missing vibrations from real speakers that move a lot of air. For mixing or listening on my pc I love the K701, if I play bass I use more bass-heavy headphones for the fun of it.
I think you can't mix the bass really good with only headphones, you need speakers for this. But with the K701 you get a really good image of everything else and there is no feel good bass that hides the weaknesses of the mix.

https://www.head-fi.org/threads/reve...ss-mod.660408/