Tone controls- to use or not?

Absolutely use the tone controls. The idea of purity of signal only applies if you have hearing in the normal range. If you don't, as most people don't at some point in their lives, then you are not hearing the music as it was intended anyway. Adjusting the strength at the frequencies that are attenuated by your physiology actually restores you to a point of listening to the music the way it was written. People forget that there each set of ears is part of a given system. I have often thought that a tweak that makes sense is to get a hearing test with a graph that shows the attenuation from normal over the audio range , take your music in a digital format and apply filters to overlay that graph so as to adjust the sound for your own hearing. You would end up with a very personalized recording. ALso a complex project that could be fun.

Most of high end preamps don't even have tone controls and all amps sold in Best Buy do. This alone should suggest something.

Tone control destroys imaging, clarity, and even tone. It changes harmonic structure by improper summing of harmonics (high quality constant group delay Bessel like adjustable filters ain't cheap).

Purists would also say that capacitors shouldn't even be in the signal path.

In addition - system should restore original concert performance. So here is the question: How do you adjust treble when you are at the concert?

Get your ears checked by a specialist. About 20 years ago J. Gordon Holt thought his HF hearing was going. Turned out he just had waxy buildup, which the ear/nose/throat specialist removed.

perhaps you might replace your cables with pure silver cables, and see if you are more pleased with the treble response.

Johnnyb53 - Good advice. Practical, to the point, thought outside the techno box. It is refreshing to see common sense.