Sorry cannot help but like Chris I be very interested in your choice

I expect you'd only manage to get yourself on the bottom rung of the Stax ladder for that budget - the price of an energiser is a serious hindrance.

I use both STAX and Grado / NVA. Both are very different, the STAX are more uncoloured, so hear-through, and extremely good at microdynamics, but they lose out big time to the macrodynamics and PRaT of the Grados. With the NVA AP10H the Grados aren't that far behind the STAX in terms of transparency, but they rock so much harder...

Thank's for yer input lads.
I do like listening through my headphones. (Mostly cds through JVC Cans & NVA AP10H)
Unlike speakers, I find headphone listening to be total immersion - Put on a good recording, have a wee dram, close yer eyes and you are transported somewhere else...!!!
So far i think its a toss up between Audeze lcd2 & Senn HD800's but this is only going on the reviews i have read...
I unfortunately cant demo them up here in the highlands (it woud be great to visit a place like thehifilounge).
The hd800s seem quite legendry, but noticed a few folk seem to find them a bit Bright / Forward Mmmmm i do like calm.
The web hunt goes on....Thanks again.

Thanks Stanley but my AP10h is a lovely sounding headphone amp, all be it without the Capella's bell's n whistles.
But does'nt yer post kind of prove what many have found to be the case, That if indeed you need to twiddle the depth and HF controls to tame the beastie's then perhaps the HD800's are after all a bit too bright and forward to begin with. 
Not so much the wrong Head amp as the wrong Can's perhaps..!!

I really think Chris is right here.  For the sort of lolly you're proposing to spend, and considering the fact that headphone sound and, importantly, comfort is a very personal thing, I'd say that extensive auditioning is vital.

Head FI is a very useful site for headphone user. Cans are a very personal thing-one mans meat is another mans poison! Comfort/sound/amp are all subjective. If you want to just zone out with a couple of halfs the senn 650s have got to be on your shortlist.
I like the senn in house sound and the attention to detail regards comfort and cable isolation.
HD700s and HD800s are both on my wish list but both require to be amped properly to work at their best.(Im in the market for both)

The type of music and environment you listen to the cans in is also a factor.

The Capella thread gives an indication of what the tune ability of Stans HPA can bring.

Pulled the trigger on a pair of HD700s hopefully a nice upgrade over the 650s without throwing the baby out with the bath water!

I have not heard the AP10h, but I have heard from a couple of owners of both the AP10h and the Capella. It's entirely up to any of them to post their own independent opinion after clear reflection on the individual merits of both. But so far I am encouraged by what I have been told by owners of not only the AP10H, but many other headphone amps.

As for the controls on the Capella: read the development path and reasons for them on the AoS forum thread.

the HD800 is difficult to drive, and with good reason. It has a 55mm driver, which is a size more commonly found as a midrange driver size on a pair of three way speakers powered by a decent power amp. A lot of headphone amps are not designed for that kind of application. Headphones are supposed to be voltage level dependent after all, whilst speakers are supposed to be current level dependent. Cans like the HD800 and the Audeze range are a halfway house designs that need both current and voltage drive capability from the headphone amp. And those kind of headphone amps are far and view between, especially below £1K.