But, once you get into Analogue mixers and such, especially with the addition of other gear, is not gain staging the most important factor when it comes to noise, hiss, distortion and the like.
The point is, any mixer, even I assume an SSL though I never tried this, will have hiss if you plug in a synth (for instande) and open up the gain all the way. So, it is always a matter of degree and always matter of the signal to noise ratio.