I find so much of what goes on in high end audio very confusing and it leaves me scratching my head. We've hit on things like this before but once again just today it kind of slapped me in the face once more. As I sat in the porcelain library reading, I came on the Sept 2017 Stereophile review of Dan D'Agostino Master Audio Systems Progression Mono amplifier. I could pick out many details of this review to highlight but I'll just relate what is detailed in the very beginning of the article. How is it that a designer/manufacturer of supposed stellar reputation like D D'A, deliver to the "premiere" audiofile publication, an amplifier so defective OTB? Not just in one area, the internal cable issue, but also the transformers in both? How does this happen with a $38,000 product? Where is the QC, did no one care enough to measure and listen to the first production run before releasing it to the public, let alone send out for reviewing. Seems like the more you spend in this "hobby" the less assured you can be that you'll get a product that is working to spec, or remains so for long. If you have the stomach for it, read the entire article along with Atkinsons full measurements. See how many other things you find that make you go HUH?
"Alas, when D'Agostino's longtime associate Bill McKiegan visited my home to install the first pair of Progression monoblocks manufactured in their initial, limited production run, technical problems intruded: First, a loose ribbon cable in one monoblock's chassis caused it to emit a loud noise. Although McKiegan easily reattached the cable—its new header and pin should prevent future problems—both monoblocks continued to emit an annoying hum that made listening a chore, and compromised all sound above the bass region. This second problem was traced to improper potting in the transformers, an error on the part of the transformer provider, and has since been addressed."
Read more at
https://www.stereophile.com/content...monoblock-power-amplifier#h0Js2bW3jd6fPeS7.99