I recently bought a Sunn Solarus from Ebay that seems as though it needs some new tubes. The problem is this is my first tube amp and I'm not sure what tubes would compliment this head well. It's the earlier all tube version of the head with 2 6550's and a 5u4g rectifier. Also I know that the amp will need to be rebiased and I was wondering if anyone knew what the readings should be for this amp to sound the best.