It's a nifty sampler plugin for FL Studio, the very cool part being that it's multi output. Indeed, when you start an instance of SampleTank (by adding a FL Studio channel) and look at the SampleTank interface that pops out, you have the ability to load up to 16 sounds, each of which is assigned a midi channel (not to be confused with a FL Studio channel). Now, don't get too excited because only one sound is available for the SampleTank FL Studio channel you've just added. So how do you access those other sound channels?
The answer is the FL Studio plugin called "MIDI Out". Remember the midi channels that are assigned to the sounds you loaded in SampleTank. Well, if you add a new FL Studio channel with MIDI Out and set the midi channel to whatever you have in SampleTank, you magically have access to the corresponding SampleTank sound (make sure the port is the same in MIDI Out and SampleTank).
Of course, you could launch instances of SampleTank for each sound you want to use as a FL Studio channel but it's very inefficient cpu and memory wise. So, it's better to load one instance of SampleTank and use MIDI Out plugins to access the actual SampleTank sounds.
The video below shows you how to access the sounds in SampleTank using instances of the MIDI Out plugin in FL Studio 9.
If you double click on the video, you'll go straight to youtube where you'll be able to change the display settings to 480p and watch a much larger video.
By default, all midi channels go to whatever FX channel you have assigned to the SampleTank instance. If you want each midi channel in SampleTank to have its own FX channel in FL Studio, you first need to change the output values of the MIDI channels in SampleTank. So, use the mouse wheel to change the "OUT" to "3+4" for the 2nd midi channel, "5+6" for the 3rd channel, etc. You then need to go into the SampleTank fruity wrapper settings, click on the "PROCESSING" tab and assign an output for each SampleTank midi channel. Now, how does that output relate to the FX mixer channel (insert) of the MIDI channel? Good question! Add the FX channel number assigned to the SampleTank instance to the output number and you get the FX mixer channel (insert) of the MIDI channel. So, for example, if your SampleTank instance is FX channel 5 and if you put "---" for the SampleTank 1 output in the PROCESSING tab, the FX mixer channel for MIDI channel 1 is gonna be 5+0=5. If you put "1" for the SampleTank 2 output in the PROCESSING tab, the FX mixer mixer channel for MIDI channel 2 is gonna be 5+1=6. I am sure you get the idea.