Paul:

You jogged my memory about an important issue: When purchasing output tubes, it is VERY important to buy matched sets. If you don't, one tube may glow cherry red and the other be normal (not to mention the mis-matched audio between the tubes) when the correct bias is set unless the amp has provisions for setting the bias independently for each tube. The Dynaco ST-70 has just one bias adjustment for both tubes, so they must be a matched set.

[This message has been edited by soundhound (edited January 18, 2003).]