I think running the bias too high will shorten the life of the tubes for one thing, which might be a bit of a concern with 12 PER SIDE !! In my experience, I have found that a higher bias results in a crisper sound, while a lower bias results in a warmer sound. I'm sure this varies from amp to amp, but that's what I found on two tube amps I have owned. In general, I think it is best to set the bias at the recommended amount. You never know if you are straining the power supply by setting the bias too high.
