Way back when, I used the contour button on my dad's Fisher 500C all the time. Since then, too much of what I've spent on fancy interconnects and cables comes down to what "loudness" and tone controls do with a button and knob. I would definitely use them if my gear had them. When I do upgrade, I will be looking for these features, even though I understand the virtues of a not having them in the circuit. On balance, I think the ability to tailor the sound to your taste and to your listening room outweighs the theoretical disadvantages to the signal path. It's about enjoying the music, not reaching some holy grail of perfection.