I really miss not only the tone controls (a fair percentage of my favorite music was recorded in less-than-audiophile quality sound), but also the mode (stereo/mono/left/right) and balance controls all pre-amps used to have on their front panels, including the Dynaco PAS 2, McIntosh C26, and Audio Research SP-3 I have owned. It was the first Levinson pre-amp (designed by John Curl) that made tone controls on a pre-amp render said pre "unworthy" of being considered high end, and started the trend towards minimalism.
I have an ARC LS-1 in my rack solely for it’s mode switch, and have considered replacing it with an older Mac just for it’s tone controls. Now I don’t have to! Mike Moffat understands ;-) .