For sale - my HD 660S, in great shape. All stock stuff, boxes, cables, etc. I did add little ModMic magnet attachment that could be removed if you wanted. These come from a smoke- and pet-free environment.

I've also got some extra pads and cables to include a la carte if there's interest.
The extra pads are the Drop 6XX/58X hybrid (top pictured +$25) and the Dekoni elite velour (bottom+$10).
Extra Cables include a stock 6XX cable (+$20; the 660S comes with a 4.4mm, longer 6.5mm and awkward short 6.5-to-3.5mm pigtail)
Hart Audio headphone cables - $15 for the shorter 18" headphone split, and $25 for the longer 4.5ft cable

The whole thing is in excellent shape. There's some minor wear on the outer box. Mostly looking for a sale, but willing to consider trades, particularly if I can trade up, and also include the Focal Elear and Schiit Valhalla 2 that I will be posting for sale as well.

I'll cover fees and shipping to CONUS. Thanks for looking!

I've also got a Valhalla 2 and Focal Elear for sale if anyone is interested in bundling.
https://www.head-fi.org/classifieds/schiit-valhalla-2-in-black.41862/
https://www.head-fi.org/classifieds/focal-elear-w-dekoni-fenestrated-sheepskin-pads.41592/