Dennis Moore wrote:
Mr. Nousaine,

Care to do like Harry and gives names and company details.

Whether it is or not I don't know. But your anecdote has all
the markings of something made up.

Hardly. If you like, I will seek out the online diary
of a recording engineer, where he recounts the commonplace
occurrence of 'sweetener' knobs in control rooms, which
exist ONLY to placate annoying record producers looking for
that 'extra something'.

The knob isn't connected to anyting, but careful
adjustment, in sight of said producer, accompanied
by asking 'Does that sound better?" seems to always
do the trick.

IIRC I once found a website *selling* such flimflammery
to studios, with a knowing wink.

--
-S.