There are several sources of additional audio material.

One important issue is to be sure you have the permission of the copyright holder to use it for public or commercial purposes

The Soundpool 16 collection is all of the soundpools for Music Maker 16 Premium version, so we have to assume you are using MM-16 Basic.  This would also mean you are familiar with all of the other soundpool DVD's available.

http://www.magix.com/us/soundpools-media-packages/

You can use ANY of these with MM-16, however some of the older ones won't use the numbered bars above the media pool to choose different keys.  They will show up as individual audio objects in the media pool.

There are not a tremendous number of vocal objects, but you'll certainly have many more than you do now.

Another great source is the CATOOH website...

http://www.catooh.com/us/

At CATOOH, there are all kinds of collections, instrument and vocal groups to choose from.  I believe they all have their beat determined, so they can be easily integrated with MAGIX soundpool objects.

There are many loop CD's available. There are looping websites that offer loops, often for free. And, there are random websites that have all kinds of free WAV's and MP3's. Again, for all of these you will need to be aware of any copyright issues.

Also, these objects will not have a determined beat, so you will need to use the Beat Finder in MMM to determine and set the tempo of each object.  Otherwise, you will not be able to use all of the functions in MMM to intergrate them seamlessly with soundpool objects.

Finally, of course you can make your own vocal recordings.