Thanks everyone for the input so far. Want to make sure I'm clear there is no harshness or edginess and the amps aren't lean sounding, it's really a case of wanting a bit more of something than overcoming a deficiency. Call it audiophile greed... :-)
A little more on my amps they are a two stage direct coupled design with a separate power supply for each stage. The driver tube is 7A4, power tube is of course 2A3. Rectification is by type 82 and 83 mercury vapor tubes. Here's a link to a long discussion about them from a few years ago. http://www.whatsbestforum.com/showthread.php?4279-Found-Music-2A3-Amplifier/