Why do designers/manufacturers...?

Most manufacturers are completely unaware of audiophile tweaks.

Peter Walker was an outstanding designer for his time.

Tomcy6, funny that your examples of tweaks that time forgot are two of my favs: Mpingo discs and the Green Pen.

The manufacturers don't put any tweaks in their product, plain and simple. Their designs don't need tweaks, at least that's what they say. Unless you are saying that expensive capacitors are tweaks. Which I don't. We already know they don't put in better fuses or better power cords. And the amp manufacturers just leave their transformers just sitting there with no remedy for the rather large and toxic magnetic field. Sigh.

;-)

The Mpingo discs, even ONE in the room, bring a certain sweeteners and warmth to the upper bass and midrange. But the drawback is you have to find the place or places where they work. For that reason, many audiophiles opt out. Most audiophiles never heard of Mpingo discs so how can they forget them? :-)