Iain - these DHTs are quite a bit better than a 6SN7. I'd suggest you
try this for home use rather than studio at this stage, and see how you
get on. the usual recommendation is the 26 because it's good and
plentiful. Personally I find it warm (think 300b - but some colleagues
like this fuller sound), so prefer the leaner sounds of the 30 and 31,
which are cheaper than the more widely used 01A, 12A and such. There's
a family resemblence anyway, so you won't go far wrong. I don't think
it's neessary to splash out on the 71A or 10Y though they have their
fans. There are a stack of European DHTs as well, and one or two
octals, plus some double triodes (loctal, octal, 7 pin bases) which
have a common cathode. Lastly there's the wire leadout miniature 5676.
I have all the above.

Email me if you want details of the filament supply we're currently
using. We're trying to make some PCBs for the filamant supply, should
come through in a month or two. Andy