If you are peaking at the master channel’s stereo out you need to either lower the volume master fader, adjust the levels inside the mix or put an limiter or compressor & limiter in the master’s inserts, as we know.
Lowering the level with the master fader is not such a dramatic thing to to. Due to the technique Nuendo’ audio engine uses, the negative effects are so minimal that I have not yet heard any.
Big K