Hi everyone,
I bought two iRig Pro Duo, the second because I thought that the other one was faulty.
I discovered that the device himself doesn't detect any signal coming from my bass guitar.
I plugged a jack coming from my macbook headphone output and played a YouTube video, and it worked, so the input port of the Pro Duo is working.
The bass is a G&L L-2000 Tribute and tha jack cable is a Stagg SAC3PS DL.
They both work fine with another audio interface I have.
Carlo