Usually doc, the Peak light that is on most mixers is set somewhere between -4 and -8dB BEFORE the circuit starts to actually clip. Think of this as being a "dummy light" more then anything else. If the light blinks a little bit, pretty good chance that you are about where you want to be. Check your manual, or call tech support for your console to inquire as the were they set the Peak LED light to engage (what ACTUAL level).
Another couple things to consider about Peak LED's and what circuit distortion in general.
Whether you can get away with a bit of clipping depends a lot on the signal that is causing it. Lower frequencies last longer in the time domain, thus, if they cause clipping, there is a better chance that you will HEAR clipping.
Higher frequencies are very short lived, and thus, clipping them will obviously mean a square wave on the resulting signal, but the transient peak may have been so short lived anyway that you probably would have not heard a difference between it clipping and not clipping. This is a trick that is very useful.
If you are for say, using a overhead mic on the drums, don't feel shy to engage in a hair of "clipping" on it. This will help you get the most sound to noise ratio, and if you can get it to clip enough without HEARING a bad kind of distortion, this clipping can in effect "warm up the track" as most like to say. You are cutting off the transients, thus creating a smoother sound.
This is obviously not something you would want to do on say a kick drum, bass guitar, most keyboard patches, etc.....These instruments tend to have a lot of low frequency content that can easily cause audible distortion. But something like clean guitar, snare drums, drum overheads, some vocal tracks, percussion in general, etc.....can benefit from a hotter signal to tape by clipping the preamp a bit.
As with most things, this is something to try out. You will have to get a "feel" for how far you can clip your preamps on any given instrument before you hear distortion. Once you do though, you will find yourself really pumping the preamps pretty hard to get the most out of them. Tube preamps definately give you even more room to play than solid state circuits do, so if you have one, do play around with running it hot. I would suspect that the reason that many don't see the big deal with a preamp like the ART Tube MP is that they never ran it hot enough for it to get "that sound".
Ed