Fluorescent lights, LED lights, dirty power can all have an affect, although I find this less so on the KPA than a regular valve ( for obvious reasons) at like for like gain settings.
I find I can effectively eliminate any noise using the 4:1 noise gate stomp from any set up though so you should get it sorted.
In other words its unlikely you will get problems live...
I was messing around with this the other day, and it really is a great solution. I was kind of surprised at how far I could crank it without it prematurely cutting off softer notes. Really good.