Yeah jailbreak + external DAC support has been pretty iffy. I dunno if that one digital out via camera connection kit Cydia app still works. The ODAC does work with the CCK if you don't jailbreak it from what I've read.
Waat, that's stupd!
Wow, just popped some Meelec large tri-flange tips on the Dunu DN-23s since I wanted some boosted bass on Thrift shop.
And wow, I must say... Isolation with tri flange tips... Holy crap!
My air conditioner (55dB by my measurements) is hardly audible with no music playing, and I can't hear ANYTHING with music playing.
Have you tried Etymotics triple-flange tips? Those are pretty hardcore. Compared to Shures triple-flange, the Etys are much stiffer and harder and they hold in the ear much better.
I have bought those Ety.Plugs ear plugs and boy do they do their job well at attenuating the sound without sacrificing sound quality though the problem is that they don't attenuate the low frequency as much as the rest but that's expected because of bone inductance.
Yeah, I have the Ety tri-flange tips, but they don't have a long enough stem to work well on my old GR07s. Because of that, they didn't seal very well in my ears and isolated fairly poorly.