E55L is indeed very linear and sometimes expensive. I was lucky to find a good number in my collection.
For those interested. I've tried my hand at a schematic.
Any suggestions (by the BH crew) for improvements for this amplifier? Do let me know!
I started with the a very basic setup as a first try.
With the HD800's it's perfectly silent and has adequate power (even from the 2Ohm tap); a perfect single watt.
I enjoy it a lot! Here it is with Mullard Mitcham factory E55L's. I prefer these over the Amperex USA build E55L's for now.
Those are the only two plants for E55L I know about. That's it for tube rolling...