I have never had an issue with one box having increased voltage rails feeding another box without.Increased headroom for whatever reason might damage the next/device following piece of gear that might not have designed in safety belts in order to protect from input voltages exceeding their supply voltages. Just read the Abs.max.ratings in datasheets of not that unusual suspects, such as NE5532, NE5534, AD797, ... , stating "The magnitude of the input voltage must never exceed the magnitude of the supply voltage".
Let's hear from the OP.
Do you feel lucky?Higher rails are not just for headroom. Sometimes things will perform better, e.g. a 12V signal might be of a higher fidelity with 24V rails instead of 15V.
When I was in the power amp business we paid a lot of attention to THD wrt approaching saturation... The power output specified with 3% distortion can look significantly better on paper (spec sheets) than power output with 0.1% distortion.I haven't seen anyone suggesting to do that.