I just picked up an AmpliFi 100FX yesterday and tried it out with two L3t speakers. I used the L and R main out of the 100FX and plugged into the Line-in (2 RCA plugs) in the back of my L3t. This frees up a mixer channel and gives me stereo between my two L3t's. Songs on playback sound great too with this set-up. So I think this is the easiest option for using the amplifi with song playback.
I'm going to try mono out into channel two tonight (like you have tried) and set the playback EQ on the L3t to "guitar" to see if this would be a decent alternative to playing through a guitar amp when I play with a group.
Regards,
Bill
