Gosh I have these too. With all due respect sir, your impression of these babies' bass is just... wrong. Your impression sounds quite typical of a pair of cans that's underpowered and I suspect the energizer is the culprit.
These cans have some of the hardest hitting electrostatic bass I've ever heard, when paired with a proper amp of course. I built a KG Grounded Grid just for these, running at dual 400V rails and 500V bias (drifting up to 520V when warmed up), and they are absolutely wonderful.
The resolution is definitely way above the HE6 on dynahi. The tonality is definitely warmer than the 009(non s), with a more full-bodied sound. The soundstage is expansive and immersive, and imaging is clear and precise. It is definitely one of the most engaging headphones I own, and one of the most versatile cans I've heard. For one moment they could immerse me in an orchestra, while the next I would find myself tapping my feet to Zedd and Ed Sheeran.
Here's the best part, since these are so cheap, I can open them up and modify the tunings with some extra filter paper. I added just 1 layer to filter off some of the treble sparkle. I guess anyone could just modify it to his preferences.
I don't own either stax 009(s) or 007, so I can't do a direct and detailed comparison using the same set-up, but from my impression (bias alert!) of the staxes on T8000 amp at my local audio shop, these DIYs are slightly less detailed than the 009s but warmer and slightly more intimate. They sound more like the 009 with a more thumpy bass and more intimate vocals. However, do take this comparison with a big pinch of salt.
BUT, there are a few downsides to these hidden gems though.
One, they are super insensitive and a b*tch to drive. On my Grounded Grid with Susy Dynalo (running at dual 20v) as pre-amp, these ES cans needs almost 70% volume pot position to sound loud enough. When the grounded grid amp is driven to clipping, the cans are only at a volume that is just barely unbearable. This is probably due to the monstrous diaphragm size, of around 90mm in diameter. Not sure how they will fare with a standard 580V bias and dual 450V voltage rails. I might do some destructive testings when I grow tired of these, but I don't see that day coming anytime soon.
Two, they are massive. Each side uses a massive 11cm earpad. This is definitely something that not everyone can get used to, and can feel bothersome when I turn my Asian head to the sides.
Three, the workmanship is truly DIY-level, with the kind of quality that you won't expect from a branded product. The driver housing design, though light, is not original, and is made of 3d printed nylon. It is electrocution proof, but I'm not so sure about the durability of this material compared to say, aluminum in the long run, especially after prolonged sun exposure for years.
But heck, why would these points matter. The headphones sound miraculous and I don't need to put on a C-collar to wear these, that's all I care about.
Edit: added the part regarding tuning. Someone needs to create a chifi thread in the summit-fi forums haha. Their humble origins shouldn't dictate their position on the Head-fi heirarchy.