Why do designers/manufacturers...?

Audio manufactures are like meat butchers, they want to sell the highest quality product at the most competitive price and they will let the consumer "season" it to their taste.

Most manufacturers are completely unaware of audiophile tweaks.

Because they make more money that way-geeezh !

Geoffkait:

Are you claiming that most manufacturers are not aware of old rusty springs and/or hair dryers?

For me "Rlwainwright" said it all. Case in point, QUAD ESL 63 loudspeakers still sound wonderful (not perfect) after all these years. If Peter Walker (the designer) thought they could have been improved using audio voodoo, I am sure he would have done it. In fact, he thought so little of audio voodoo he was prepared to argue, and demonstrate at length, things like expensive speaker cable had no noticeable improvement on sound quality. Oops, this is going to upset someone!