http://www.tnt-audio.com/ampli/dynaco2e.html
The above article says something about the Dynaco running class A up to about 15 watts. I cannot say that I could agree with that after looking at the output on a scope. It looks like it falls short. In another response it is stated the Dynaco's power supply is good for 200mA. In my estimation it doesn't have the necessary force available to put out 70-85mA that I believe necessary to put it into class A operation. Secondly as you increase the current to the tube you may find it necessary to decrease its operating voltage in order to stay in line with the capabilities of the tube. I fully believe that if your looking for a sense of sonic purity that you find lacking then the best way to go about this is a driver board swap. Frankly there is a night and day difference between the junk driver board in the stock Dynaco and about anything else out there. As I stated in an earlier post I have put several of my Dynaco's up against what should have been much better amplifiers. The modified Dynaco outshined several 3ooB's a 45, and a 2A3.
As stated by Ty_Bower
In a simple sense, yes, you would have to raise the current until the tubes are forced into pure class A during operation. In reality, you can't just do that. The power transformer can't supply that much current, and the tubes would exceed their dissipation limit. I don't know enough about the way pure class A amps are designed. Maybe you need to lower the B+ so the tubes can handle higher current, but now we are starting to talk about a total redesign of the amp.
Slartibartfast I don't see where you are finding that the transformer is capable of handling it.