MF-P01 volume increase

[Beast]

I use a Tascam MF-P01 4-track for working on guitar riffs. The problem I have is this: I record the first track, rewind, go back to overdub the second track - say a lead or other rhythm part - and when I press record the volume coming out of the headphones increases by a large amount. This wouldn't be a problem except for the fact that it makes overdubbing difficult in that I have to constantly change the input level and level on the first track to get it to a good place where I can both hear the second guitar part I'm playing AND the first recorded track. Anyone know if there is a way around this? In the manual it doesn't mention anything about the volume output increasing once you press record.