Hi Guldmann
From what I gather you are planning to control multi channel audio at preamplifier level if then I don’t think you have to use relays in the feed back path of your opamps, try using the 4066 quad bilateral switch Ics that way you can save money,space 4 ICs = 16 relays and no relay click and you don’t have to use DAMPING DIODE across the relay coil to eliminate undesirable FLY WHEEL EFFECT caused by transient current through coils