GAIN IS at maximum, so a passive system "attenuates" the signal to the amp providing the source (a CD player) is passing enough signal to the power amp. I love preamps for two reasons- dubbing tapes where possible- a disappearing feature unfortunately, and precise control over the volume. This adds distortion, but frankly, I don't give a damn. I wouldn't even mind occasionally having/using a loudness switch, but only for crummy recordings.
BTW, some guitar pedals ("stomp-boxes") are truly amazing sounding and musicians can switch them on and off without stopping playing to adjust a rack-mounted preamp. They can be wired in series on a board and the tail end goes to the amplifier(s). Some guitars have gizmos inside to get different effects but need a 9 volt battery to power the circuits.
BTW, some guitar pedals ("stomp-boxes") are truly amazing sounding and musicians can switch them on and off without stopping playing to adjust a rack-mounted preamp. They can be wired in series on a board and the tail end goes to the amplifier(s). Some guitars have gizmos inside to get different effects but need a 9 volt battery to power the circuits.