I do not have the HD800S, just the original HD800. I always assumed that the weak bass was as a result of lack of power from the Hugo 2 so when I was in my US home for the last six weeks I left my Stax gear in the UK and took my TT2, M Scaler and HD800. I plugged in the headphones and started listening to track after track and could not believe how weak the bass was. It was if it had been electronically filtered out. The treble was not pleasant in all regards, the sung S sounds had a sibilance that was hard to live with, although the high frequency percussion was really well differentiated. Honestly, if I had bought a system of the HD800, HMS, TT2 and heard this I would send them back and try something else.
After seeing these strong statements I decided to do some more testing today. Now I was testing the Stax 007 Mk2 with KGSSHV Carbon drive unit against the HD800, Hugo2 and the TT2/HMS. I did not really detect more bass on the TT2/HMS than with the Hugo2, I was shocked but I consistently found this. Whatever causes the weak bass on my HD800 did not seem to be a lack of power. Perhaps the HD800S has been engineered with better bass but here was a set of headphones I really enjoyed in the past being revisited after more than a year and I could not listen to them.
I would hate for someone to go out and buy a TT2 to cure an HD800S and be disappointed. Clearly we all hear things differently and I would urge someone contemplating this arrangement to hear it first. I was listening at -5H on the TT2, red book, no filter on the HMS. I really wanted this to work for me but they are not for me.