This is one of audioland's dirty little secrets. The signal passes through miles of wire in the recording console, often with seperate EQ, compression and processing indepedently applied to each track. The producer, engineer and mastering technician all have their chance to "sweeten" the signal. Then we are Satan's sound men for passing it through a pair of bass and treble controls, which may actually correct certain frequency response and phase anomolies created in the preceding processing, and yes, trading some transparency for it. Are we supposed to move our furniture and change our cables each time we want to play one of those Mobile Fidelity recordings that have screwed-up frequency response, not to mention the gazillions of other recordings of beautiful music that suffered at the hands of record industry hacks? El is correct as well, the newer EQs, which operate in the digital domain, have much less deleterious effect on the signal, though us analog guys probably won't want to digitize the signal just to use them.