Thanx again. Finally the only way about looper was to: Plug the line out from the back of the street ex into your looper, then go from looper out into the aux in on the street ex...
The way with 3th channel did not work
As for the sound, i just did realize that i have chosen clean mode and not the acoustic one. It sound more natural to me.
In any case my main question if this preamp would make cause a damage in the amp. I may try a compressor + boss ge7 eq in order to give the final touch to my sound.
I think that is better to get over the inside fx
Many thanx