Is This Trip Really Necessary?
    The first step prior to optimization is to ask ourselves if we really need a power amplifier. What are we trying to drive? If the load is a severe one, such as the Grado headphone's 32 ohms, then we certainly need a power amplifier. On the other hand, if the load is a 100k potentiometer, then we should not forgo the simplicity of a single-ended amplifying stage, such as the Grounded Cathode amplifier, a Cathode Follower, or a current source loaded Grounded Cathode amplifier. You see the whole point to a well designed push-pull, Class A amplifier is that it can deliver up to twice the idle current into the load, whereas the single ended amplifier can deliver only up to the idle current into the load. Do you need that much current?
    How much current must be delivered into the load? If the amount is less than one fifth the normal idle current of the tube you prefer to use, then stick with single-ended circuits. If the amount is greater, then first consider using a beefier tube with more idle current. Do not fall into the trap of past practices: it used to be done this way; therefore, it must be done this way. Let the past inform, not restrict. (Aluminum foil meatloaf was a 30-year-old popular recipe that was going to be added to a cookbook of great American dishes. The recipe called for making a ball of aluminum foil and adding it to the meatloaf. The editor of the cookbook wished to discover the origin of the recipe and found the chef, who when questioned about her inspiration to include a ball of aluminum foil, replied that she had to jam the aluminum foil into a corner to keep her cracked pan from leaking. Or maybe you have heard of the Buddhist tradition of tying a cat to a tree during meditation. A great monk was often pestered during group meditation by a cat that lived at the monastery. So the rule was to leash the cat to a tree until the meditation was over. Even after the monk's death the cat was leashed to the tree and even after the cat's death, a new cat was found to be leashed to the tree. Many treatises were written about the meditative importance of a leashed cat.)

   If you think vacuum tubes are expensive today, you should work out in absolute dollars the cost of tubes in the 1920s, 1930s, and 1940s. So too all the parts associated with tubes, the coupling capacitors, chokes, power transformers, and diodes were hugely expensive. Thus arose the need for economical design: fewer tubes and less current, as less current meant smaller, cheaper parts and power supplies.
   Today, with the vacuum tube having made its home in the luxurious, cost-is-no-object world of high-end audio, the need to keep current consumption to a minimum does not apply. Yet for many tube gurus, the rule of thumb is 1 to 3 mA per small signal tube. While this amount of current draw is adequate for the 12AX7 and the 6SL7, it is not so not for most other tubes. A 6DJ8 sounds terrible at 1 to 3 mA, as does a 5687 or even a 6SN7. In general, an increase of current equals an increase in linearity. The bottom of the plate curves is not where the tube should be run. As a tube nears its current cutoff, its distortion increase greatly.