Mainstage is a great application, (only available for Mac), that turns your Mac into a workstation to use both live and in recording situations. It's packed with instruments, effects and other goodies.
Now, a thing that peopla are a bit unaware of, is the fact that you can load your EXS24 instruments into Mainstage! Here's a short tutorial written by John Maroli.
This tutorial is for installing and using EXS24 instruments in MainStage 3. Used in this tutorial was MainStage 3.0.3 and Mac OSX 10.9.3
Installing EXS24 Instruments in MainStage 3.
Download your instrument and unzip all files. The instrument folder that you need will contain files ending in “.exs” and another folder containing all of the individual audio samples. In this case, the instrument is the Sampletekk Black Grand Medium Ambience.
Go to your user home folder and open the “Music” folder. Within the “Music” folder, open the “Audio Music Apps” folder, and then the “Sampler Instruments” folder as shown in the following image. The full file path to the Sampler Instruments folder is /home/current_user/Music/Audio Music Apps/Sampler Instruments, where “current_user” is the name of the user’s profile. The “Audio Music Apps” and “Sampler Instruments” folders should have been created when MainStage 3 was installed, however they should be created if they do not exist.
Place the instrument folder like the one shown in step 1 into the “Sample Instruments” folder. The instrument is now installed.
Open MainStage 3 and create a new concert or open an existing one. For this tutorial, I am creating a new concert using the Keyboard template. MainStage 3 cannot be open during installation or it must be restarted.
Add a new channel by selecting the “+” button in the upper right hand corner.
Add 1 instrument with the settings shown in the following image.
Select the “Instrument” drop down box in the “Input” column of the newly created instrument as shown below. This will be in the Channel Strips portion of the window.
Select EXS24 (Sampler) > Stereo.
A window will appear for the EXS24 Instrument as shown in the following image. If the window does not appear, click once on the center of the Input instrument drop down box that you just selected where it now displays “EXS24”.
Select the instrument drop down menu as shown in the following image and select the instrument that you installed. In this case I am selecting the Black Grand Medium Ambience 1.
The instrument is now playable via MIDI input. If any other instruments in the Channel Strip are on, then they will play with the newly installed instrument. To turn other instruments off, hover the mouse over the instrument name in the “Input” row shown in step 7 and select the power button that appears on the left.