Probably... Perfect is difficult to achieve in anything, I'm assuming 0.1dB or better is "perfect" here.
For an analogue pot style of volume control, then there could still be some residual contact resistance even at the end stops, but it is probably "perfect".
For a switched attenuator style of volume control (which should have "perfect" channel balance anyway), then unless it is faulty the maximum setting will be perfectly balanced.
Digital attenuator volume controls already have perfect channel balance.
Hope that helps!