Hi, I have a question if you would like to use a separate preamp, in my case an Avalon 737, and you would connect it to the SQ5, before it arrives you actually used 2 preamps, right? my question is, can you bypass the sq5 preamp? or do you always have to use these preamps? otherwise it would be a shame to use 2 preamps 
let’s see what is possible
You could bring it in the ST 1/4" inputs. I’m not sure you’d gain anything, though.