[Antonmb]

When I first started playing in the higher end, tone controls were considered anathema for several reasons:
- each additional circuit brought baggage of some kind, whether it was an additional layer of distortion, raising the noise floor, or something else, so the purist idea was that it was better to suffer with the vagaries of the recording than to add some other distortion in the effort to improve the tonal balance.
- most tone controls were not very well implemented, with too broad a frequency range, so turning the treble down may have tamed that 10k peak, but it also sucked out the harmonics above and below it.
- tone control circuits were considered a diversion of funds that could have been used to improve elsewhere - better to spend the money on higher quality components than tone control circuits.

It's now questionable whether any of these reasons still apply. A company like McIntosh certainly knows how to properly implement a tone control, the cost of parts to do so is probably negligible at McIntosh prices, and electronics are so refined now that you'd be hard pressed to hear any detrimental effect from the additional circuit if done properly.

So the issues in the early days of cheap Japanese receivers versus purist equipment, in reality no longer apply. As others have said, tweak away and enjoy the music.