Correct - not a direct answer. But I will be following up with him on this and other similar questions.
BTW, don't underestimate the stock tube configuration. I think I personally had become somewhat infatuated with the idea of rolling tubes, and a subsequent experience has me wondering if what I heard was due to the way I had my cables dressed, because I experienced hum again, then remembered the cautions documented in the owners manual about the sensitivity of the preamp to nearby external sources of electrical fields. Re-dressing my cables eliminated that hum.
BTW, don't underestimate the stock tube configuration. I think I personally had become somewhat infatuated with the idea of rolling tubes, and a subsequent experience has me wondering if what I heard was due to the way I had my cables dressed, because I experienced hum again, then remembered the cautions documented in the owners manual about the sensitivity of the preamp to nearby external sources of electrical fields. Re-dressing my cables eliminated that hum.