Thanks Diki...I guess the only way to really tell if it will have an effect is to actually try out an SA1000 with my S900.

Yamaha doesn't make keyboard specific amplifiers such as the SA1000, or the KC-series, and some of my clients are looking for a manageable amp/speaker without having to buy a P.A. like the Stagepas 300/500.

I'll have to check it out...my local store will probably bring one in.

Ian