I love it when I discover a capability in some software I already have. Here's a video from InSession Audio that shows how to use Komplete Kontrol to audition Kontakt instruments without having to load them. No proprietary hardware required.
 

 
P.S. This is where you chime in with "I already knew that, didn't you?" Well, nope, I didn't.

Neither did I. This is pretty handy...thanks for posting.

I already knew that, didn't you? Guess you didn't, did you?

Nope, I didn't know that......Thanks Bit!!

Its a great, relatively new, feature BUT it only works for NKS compatible instruments.

It will work with any NKS compatible VSTis too, so I can preview my Arturia V collection, AAS, XILS4 and all the Komplete presets.

I believe it does fill your hard drive.

Can you choose the location of the preview files?

I don't think so. They are co-located with the rest of the instrument, like other support files. They aren't very big, though. typically 0.5 MB to 2 MB in size.
 
NI is typically close-lipped about the actual details of the standard (I couldn't find any links to the SDK online), but I checked my NKS-compliant libraries and the preview samples appear to be in files having a .nicnt (Native Instrument Content?) extension.
 
BTW, here's a list of vendors that support the standard. It's a who's who of the major players, even if they haven't all converted all of their products yet.

Hey Bit. I asked this question on the Kontakt forum.

(Thinking about installing Komplete Kontrol. Can I choose the path/location of the preview files?)

Moderator’s reply:
Yes, change the Content Path in NA Preferences before installing them.

Downloaded and installed.  NA is asking for serial number to install preview files.  Anybody help on this?  I thought it was free to use.  Thx.