In message , Andy Evans
writes
Well, my pal chis found (runs the service for Beard Audio) had a 211 amp for
years, and just switched to 845, which he prefers. It's not so hard to drive -
these days there are SRPP and mu-follower circuits, good interstages - all
sorts of solutions, even pentode drivers are re-emerging (EL84, C3M etc) Andy.

=== Andy Evans ===
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The latest bifilar-wound 1:1 interstage from Sowter would be a good
choice. I've still got my DA100 triodes and the Sowter OPTs I had wound
many years ago, and a rebuild using a good interstage transformer would
be of interest.

The drive requirements of an 845 are near as dammit the same as the
DA100 (once described by Hi-Fi World as 'The Aston Martin of British
power triodes'!).

A 12B4 driver transformer coupled will do the job, but a little B9A 12B4
looks dreadfully weedy against a DA100. (Or an 845)

--
Chris Morriss