I suspect the gain control allows you to reduce the gain of a source(s) before it reaches the attenuator on your amp - this is convenient when you have a high gain source. Without it you would only be able to get miniumum use of the VC before you were overdriving you amp.
The phase control probability allow for reversal of absolute polarity. The change is subtle, works on only certain recordings, and is not heard at all by many.
The phase control probability allow for reversal of absolute polarity. The change is subtle, works on only certain recordings, and is not heard at all by many.