Will this be too much for simple XRL and RCA inputs for balanced LM3886 amplifier?

[pbilous]

I want to have both XLR and RCA inputs supported for my amplifier. Since it is fully balanced, I am wondering if I can combine two signals by summing opamp? Or is there simpler solution?

Schematics is attached.

 

[pbilous]

Here are two variants that I was trying to combine together. One shows complete signal path for balanced XLR inputs, the other shows signal path for RCA inputs.

How can I combine those efficiently?

Any help is appreciated!

 

[bebo65]

If you don't want to keep the circuit as a instrumentation amp this configuration works: