I've heard others suggest to bend the metal headband extensions; I don't like this idea as the shape of the metal extensions are set to slide into pockets in the headband and I think it's best to let them retain their proper shape. Boosting everything I think it’s typical what beginners like me do, and the bass already hurts my ears before the trebles have reached lout enough volume, so I think I have to cut it down a bit on the Mojo.

The box is a bit big though, so it like all the other boxes is in the attic, but if this was to be your only headphone, then I can see you using this box in your office or living room.Their bass is very good, consistent, and punchy, the mid-range is well-balanced and clear, and their treble is very good as well. The biggest difference I hear when switching from the HD 660 S to one of the other two, and I heard it immediately, is the fairly significant sense of a smoother and more refined sound of the previous cans. I did some pad rolling with Dekoni’s selection of Elite pads for the HD600 series, and can offer a strong recommendation for hybrid pads for those looking to fill out the bass a little bit.

Taking the design DNA of its classic, open-backed trio of headphones – the legendary HD 580 Precision, HD 600 and HD 650 – Sennheiser is reanimating the old generation by using the latest driver technology. We've added a comparison between these headphones and the Sennheiser HD 660S2 in Compared To Other Headphones.

The HD 660S performed really great when it came to its ability to distinguish the individual layers making up tracks in complex musical passages, and it did so almost as well as the Sundara, which I personally thought was very impressive.