[Ron Ramirez]

From 1933 until 1938, Philco connected their 42 tubes as triodes in most of their push-pull output circuits, as well as using triode-conected 42s as driver tubes.

Tom, you're right regarding the 2A3 and 6A3.

As for the "need" for power, no, one does not really "need" say, 100 watts per channel. I have a Marantz 2215B stereo receiver that is looked down upon by some because it puts out "only" 15 watts per channel. But those 15 watts per channel sound pretty doggone good...

And the 15 watt output of a 37-690 or 38-116 sounds pretty good, also. The 37-690 uses the octal version of the 6A3, two 6B4G tubes in push-pull. The 38-116 uses 6L6G outputs.