Miller Audio Ultimate Upgrade ST-70
My name is Randall G. I’ve been an audiophile since the late 70’s. I’ve always searched for the ultimate accuracy in sound, which meant that vacuum tubes were never in my system other than a California Audio Labs CD player in the early ‘90’s. I don’t even remember which tubes were in that CD player, it never sounded quite right to me. Still, I decided I wanted a tube amplifier, even if it only spent an occasional listening session in my main system.
I received my Miller Audio Ultimate Upgrade ST-70 on June 10th, 2025. It is a basic configuration with Auto Bias and a standard complement of tubes chosen by Bryan Miller. This consisted of 3 N.O.S. 6SN7’s and a matched quad of JJ KT-77’s. This unit is all new parts assembled by Bryan and not an upgrade of an existing Dynaco ST-70.
Because my experience dealing with Bryan was exceptional, I wanted to do a review. My comparison was to my current Benchmark AHB2 amplifier that I’ve been listening to for the past four years. It is not the only amp that I own, but the only one that has been used in my main system since receiving it.
Currently, I’m using three Cryotone 6SN7’s and a matched quad of Psvane Horizon EL34 tubes. I’m using the Miller Dyna-70 to drive a pair of GR-Research Bully speakers that I assembled. Yes, my listening room is treated. I’ve played around with cables. I have power conditioners. I use digital and vinyl sources. I like listening to music of all types but mainly listen to Classic Rock. I do not want to be cured.
Laboring over what to describe in the review, I realized that since receiving the Miller Dyna-70, I have averaged 30-40 hours weekly listening to music. At the time I’m writing this, August 29, 2025, I’m at around 400 total hours! In that 10+ week span, the Benchmark AHB2 amp was in my system for no more than 3-4 hours for comparison purposes.
You don’t need or care to hear my adjectives about the amplifier and its musicality. Yes, there are many of them. If you want to listen to music and a 35-40 watt amplifier will meet your needs, I can’t think of a more satisfying option than Miller Audio’s Ultimate Upgrade ST-70, especially at the price.