Ok.....so a nice guy, Matt, had me build some Gabon Ebony cups for his D2k's. He wanted a piano black finish. CA glue was the only choice for such a high gloss finish. These take alot of sanding and all the way up to around 8,000 grit. But oh-so worth it.
Now...prior to re-cabling I was to also dampen them with the famous Markl technique, but low and behold upon listening to them with just the cups and stock cable, I was blown away. Very detailed and punchy with not a hint of sibilance. The stock cable only had the 1/8" plug, Matt forgot to pack the 1/4" adapter, so I only listened via my HTC Thunderbolt...and I just could not believe what I was hearing. Really...I couldn't. Very impressed and these make a clear choice for portables as well.
I should explain that I did complete a small chamber modification as well, which may have something to do with the increase sound quality as well as the wood cups themselves. :-)
So I explained to Matt that further dampening is not recommended at this point but could be completed in the future. So we decided to re-cable them with a shorter, better quality all silver cable.
Through my Leben, it's alittle warm and I've lost alittle of the punchiness. I'm thinking D2k's are more of a solid state can, but they still sound fantastic.
I'd be more than happy to complete these modifications for others and will, in fact, be picking up another pair of D2k's for myself.