When implemented correctly, they can sound as good as Class A, Class AB, SOME,,,NOT ALL Tube designs.
IMO/IME they can sound better than any tube design. For this reason I think tube power amplifiers are on borrowed time.
less then 25% of the actual cost goes into the build . I owned a Audio dealership
and know from speaking with engineers ,I have seen Wild claims of 10 x mark up
There are two ways of pricing high end audio products, just as there are two ways of pricing anything else, like cameras or bicycle parts. The first way is according to a formula, which allows the manufacturer to pay all the bills and still make a profit, making it worthwhile to do it again. Typically, depending on overhead, the formula is between 3 and 5x markup.
The second way is to charge what the market will bear, based on the market's perception of the value of the product (the perception of greater value based on price alone is known as the Veblen Effect). An example of this kind of markup in the bicycle world is Campagnolo.
Equipment based on a formula will often bat well above its price range. This is especially true in high end audio where pricing to what the market will bear is very common.