Hi Luca,
There are a couple of things I want to follow up on from your reply, but for now I just wanted to ask if you had tried using the input trim on your GL that allows you to add an additional 6 dB of headroom for connecting pro gear. To be honest, I didn't even realize this was a feature of the GL until I went back to the manual after I read your latest post. So I was wondering if you had tried it.
Thanks again for your helpful replies.
Jeff