One of my favorite indirectly heated drivers for small output tubes is the 6N7 which was already presented as tube of the month almost 2 years ago. There is an electrically equivalent tube which is a predecessor of the 6N7. I have used it in the past as drivers in 45 amps. It's time that it get's it's own place in the Tube of the Month series. Here is the 6A6.
This is a 6A6 from my collection which came in a generic white box. No brand marking visible on the tube. It has a dark brown base: