The UE 6000 is a good headphone. Its passive mode is too good for most genres and makes the music sound coloured and beautiful. In the active mode, the in-built amp amplifies the low freqs so much that you'll feel the audio drivers vibrating in most demanding movie scenes.
The product is infamous for quality issues and Logitech has discontinued manufacturing the product. As such, I'm getting my refund from Logitech, as they weren't able to replace my faulty UE 6000.
Try them out, if you face any issues, get a refund. Talk to your seller and your local authorized service centre before making a decision !