Is it possible to polish marble without using powders?

Yes, it is. There are several different methods for polishing that do not use loose powders. One method is to use a polishing brick or a polishing pad. The polishing bricks are often called 5x bricks . If you decide to use these bricks you will need a special holder for your machine.
Another method for polishing is to use a polishing disc. These discs are usually the same size as a diamond and easily fit on a Velcro backed drive pad. Contact the companies in the resource directory of this book for information on these methods. One additional note, it is also possible to polish certain marbles with diamond abrasives. This will require that you use a series of diamond going as high as 3500 grit.
TIP It is also possible to obtain a polish on marble surfaces using high rpm’s. Stay tuned and keep reading the trade publications for advances in high speed stone polishing.