Over on the Wam, Rob "open door" of Aired Audio in Gloucester was a Jolida dealer & BD Audio used to either sell them or Mod them I think. Not sure if Aired Audio are still trading, but it may be worth contacting Rob to get a definite answer.
I've been using a Jolida glass mkIII for a while now. I've rolled some different valves in but haven't done any other mods to it. There are quite a few people who have had caps etc upgraded & are very keen on the results. I'm really happy with the DAC & much prefer it to the Young DAC I previously used. Nice soundstage, natural presentation, ie not forced or overblown in any one area. I can't really see me changing it for quite a while, it just does everything I want. I have a good mate who uses a Weiss DAC which is a whole load more £££ but when I come back to my system, I can't really say that I feel I'm missing out on much in comparison. I reckon the MkIII DAC is an absolute bargain.
There are a few threads on the Wam about it if you want to read a bit more.
Definitely worth getting hold of one, I'd say.
Matt.