Regarding the stock cable, I took an x-acto knife, cut and pulled out the plastic tube part which is close to the shell. Gets rid of the annoying stiffness and results in a decent fit. It was driving me crazy. I have the Dark Matter. Blows the Opus Mia out of the water. Completely. No questions. I too am a big fan of the Rah and what we have here is a rumble in the jungle version. The bone conduction is more like a presence than a sound, but the sub-bass on some live concert recordings is amazing. No bleed into the mids. This with 50hrs burn-in, I know the journey is long, but I've just decided to listen anyway. For me at least, they are that good.
With the OM I felt myself listening to details, wondering if everything soundwise was correct, quite the mathematic journey. The Dark Matter just invites you in, hands you a beer or three and puts you right into the action. Usually I prefer foam tips but for the DM I am using Azla Sedna Fit Short instead of the Tenmak foam tips. Grey-Blue filter combo. Of course after more burning, this may change.
One thing I noticed is that when I first put them in and turn on the music, I think, "this isn't that great, or right" but after 30 seconds or so, the brain burn takes over and I am at once transported deep within the recording. Addictive listening, that's for sure. Sorry to ramble, these are my initial impressions. Oh yeah, a good seal is an absolute must.
