I'm currently using a Yamaha MG 10/2 which I bought second hand. I think this model has been discontinued.
This is the first mixer that I own.
Given my rather limited experience with mixers and pro-audio equipment in general, I would be in no position to comment on the precise audio intricacies, perceptible or imaginary.
But as far as I'm concerned as a noob studio hobbyist, there's no noise, everything I've plugged into it and output through it have sounded just like how I thought they should sound. I'm a happy man.