Joe sent me a private email a couple days ago from which I gathered that he's not using the Yamaha speakers or the subwoofer, but wants to go directly from the Tyros line out to the AL's. Is that correct Joe? I did the same setup he described for my 9000 Pro and it works just fine. The cable he uses is a Y adapter ... 1/8" into the AL-621 sub and the 2 RCA into the keyboard line outs. Pretty straight-forward in my book. Why should that not work?