I love these. I bought them on a whim and they have already became my most used set of cans. They're perfect around the house. Default cable isn't obscene long, and not too short. My Monolith USB DAC/amp is a great match for them. They're a little underwhelming unamped, but honestly not bad. They're GREAT amped. Bass, while better than other 6-series, still isn't all that strong. For the price I really have no strong negatives. I haven't heard 650s in years, but from memory, I like these better.
esmneuhofThe highs open up more,the soundstage widens, you get more of a 3D realistic separation sound etc. Etc.
It was almost like 2 different headphones for me, night and day difference and I'm not exaggerating!!!!!
All you lose is a drop of bass. It's not like you don't have anymore good bass, the bass is enough. I personally like the bass better now bc I'm not so bass heavy.