Active signal blender

[Mario44]

Hello
I'm breadboarding this:

Basicly this circuit does it's job, but when I'm switching pickups in my guitar, connected to one of two inputs(no matter which), I can hear a loud "pop" sound. When I connect the same guitar straight into amp, the "pop" sound is almost none, so it looks like this circuit above is amplifying my "pop" sound comming from the pickup switch. Or maybe it's just my breadboard?
Any ideas what could be the reason of "popping"? Or maybe I should get it built on a PCB?

Btw, opamp used for breadboarding is TL074. R8 and R9 are 100k pots to adjust levels.

[PRR]

I would lean to 0.1uFd film caps at C1 C2 (maybe C3 C4).

Electrolytic caps leak, and 1Meg may not be low enough to drain a 10uFd e-cap to "zero".

[Mario44]

I had 0.1u on inputs but they were cutting too much lows. I also used 10meg resistors with those 10u and result was the same. I'll try with 1u non electrolytic caps and will see.

[antonis]

I also used 10meg resistors with those 10u and result was the same.

As Paul told, you need LOWER resistor value (to make RC time constant low enough..)

<I had 0.1u on inputs but they were cutting too much lows.>
At 16Hz..?? 

[Mario44]

I was quite surprised too, that inputs cut all bass. It couldn't be possible with 0.1u.
I took a look on these 0.1u, and they were not 0.1u but 2.2n  .  They are in the same case and when I took them from the box I thought I was taking 0.1u.
Now it sounds good with real 0.1u on inputs and there is no "pop" sound anymore  . Pulldown resistors are 1meg everywhere.