Help with a mixer

[sean k]

I've designed this simple little mixer for my music making so I can run a few of the instruments I have singly or all together with a FX loop. I want to be able to go wet and/or dry for each input and be able to shut each input down or bring it up quickly as well. I started out with opamps but it was lots and lots of them and far too complicated so I decided to go with transistors and choose BC546's because they are kinda low gain at 100-220 hfe.

I've drawn in the resistances as guess-timates so if anyone has ideas about how to make it work better I'm all eyes (ears)

The inputs will all be from fx or preamps of some description so no high impedance inputs like guitar coils or dynamic mics.

My questions specifically revolve around the collector resistors combined with the emitter resistors to set the gain and what effect the collector to base emitter has on that?

Also one set of summing resistors are 100k and the other are 10k and my question is what difference that'll make and whether they might be another value. Maybe all at 10k, all at 100k or something else?

Can't change much but I can change values.