What People Are Saying
“… At this point, I can state that this is the most profound upgrade for my system over its roughly 40 year genesis. There is little doubt that this is in part because this amp is “cut from the same technological cloth” as my big 16 ohm Altec’s but that doesn’t do justice to the sense of space, staging and focus on each musician and instrument now happening routinely in my living room. I can’t imagine ever needing or wanting another amp. It’s dead quiet and I’m not coming close to taxing this amp.
I am so glad you were specific about upgrading the power transformer and LM334s. These must be responsible for the rock solid presentation and what has allowed the bass to “unpack” over the roughly 40 hours of run time so far. It now is exceedingly powerful when called for, yet balanced and perfectly nuanced. You notice the character of different bass drums, and generic rhythmic sounds I’ve heard for years are now fully detailed. Someone hitting a hollow wood block with a drumstick (for example). Every listen to my favorites is revealing some treat of that nature. I’m about to plug up my first new turntable in 42 years and I’m sure there are more revelations coming. This is the most enjoyment I’ve had with my favorite hobby in decades…”
“…Happy to converse with any fellow Dyna-70 Ultimate builder. I’m pretty sure I’ll have to break down and build another one myself before too long…”
— George R., MS (Dyna-70 w/Auto Bias)
“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.”
“…I’m liking what I hear, no hum or any other noise and a Black background indeed. It gives about the same stage width, maybe a smidge wider, but the imaging is quite a bit better. The instrument tone is about the same, the brass especially sounds “in the room”. Vocals are where this amp really shines. I know immediately who is singing, even my wife can hear the difference in voices- from the next room! As I expected, dynamics are better, transients are quick without any edge…”
“…This mod is the best iteration I’ve yet heard in an ST-70. I just have to wait about 20-25 minutes until it opens up after turn-on…”
“…One of the things I love about this amp is the quiet background. The music just appears, my mind doesn’t have to fight through any noise. I can relax and immerse myself in the music…”
— Carlos M., TX (Dyna-70 w/Auto Bias)
“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.”
— Randall G.