Line Mixer for subgroups/fx on SSL AWS

I own a SSL AWS console, which has only 4 stereo returns and I need to create more returns so I though I might connect a line mixer, 1 Rack unit, to sum more returns down to 2 channels.



Does anyone have a recommendation for a transparent line-mixer, 8-16 channels with gain and pan. And maybe inserts too?



And have anyone done this to get more inputs on their console?

Line Mixer for subgroups/fx on SSL AWS