The simple answer is if it sounds better to you, use the tone control.
Unfortunately, if hearing is nearly gone in a particular frequency, it is difficult to compensate with a simple tone control without over emphasizing the lower treble frequencies compared to the rest of the sound spectrum.
Some cables are brighter sounding and some are darker. Silver wire can often bring the upper octaves forward a bit.
When you feel it is time to upgrade your whole system - look for the tonal balance that sounds best to you. It may be time to focus on the midrange and all the wonderful nuance, timbre and tonal colors available there. That's what I am starting to do ;)