I have a DGX-305. Is this boost volume thingy on the Z-5500?

I'm not saying the volume wasn't loud, because it was! It is the most powerfull set of PC speakers I have ever heard! But just as a comparison, my 150Watts amp and two 12" PA cabinetts blew the socks off of the Z-5500 at just 20% volume, (Z-5500 @ 100% volume).

I will try to access that "Boost" thing to see if I can get enough volume out of that...

Doc-Z