Update january 4. 2012:
Recently I have also been looking at 829 based amps,since they are really cool looking. They have pretty high B+ though, I like it as low as possible, and I cant see tha 829 bringing enough power to the Maggies without voltage in the 400´s.
My recent favorite is a simple EL85 PP. Though it will only supply 10-15Watts it can have a low(ish) 320V B+. Here are a few reference links:
This schematic is enticingly simple and well documented, with variations and "improvements" and the cool thing is it runs in class A, although most of the harmonics are evened out. But without negative feedback some harmonics may get through the push pull stage.
http://diyaudioprojects.com/Tubes/EL84-Push-Pull/ This is also a well documented design a development on the diyparadise build. For pushing towards 20 Watts I´ll explore parallel push-pull.
30.jan 2012 I decided to abandon diy on this amplifier. I bought a used Music Angel XD800 mkIII We´ll see if its suited for a new cabinet in Empire style