HD 600 /650/660 what should i buy

hi every one
i have NFB-11.28 am thinking of buying new headphones
i use the AKG K712 and wanted an upgrade
any ideas ?

Nov 29, 2019
Aside from your appearing to want others to do your research and thinking and deciding for you, you post four sentences and a title and make a total of twenty-one grammatical errors! Is this how incredibly stupid American society has become? Are you proud of your ignorance? This must set a record. You are an idiot!
Feb 5, 2018
I have HD6xx, K7xx and NFB11.32. I would say that K7xx does not synergize with NFB11. If you have only tried the AKG with Audio-gd, I strongly you try it with a different amp/DAC combo. Even the onboard amp from LG V20 or V30 can make AKG K7xx sound good (to 70~80% of its potential). If you have tried K7xx with a different amp and still want to get the Sennheiser HD600 series, HD600 series does work well with NFB11, but I would not say this is an upgrade from the AKG K700 series. My HD6xx really shines when listening to live vocals and it's great music listening. However, in my opinion, my K7xx still has its place in watching movies and gaming due to its comfort and sound stage. Also, if you like hip-hop music, AKG sounds better. Take it with a grain of salt as my use of headphones may differ from yours.
Feb 4, 2018
What compared to the AKG K712 do you want to upgrade? What part of the headphone do you go: I wish it did this just a little bit better? Do you want more bass? treble? mids? Something warmer? I'm not familiar with a really wide variety myself, but these are the type of things you need to give people for them to know what kind of headphone would be an upgrade for you.