Around 2010 I had bought Guitar Pro.
I have searched on this Windows-PC for WAV Files and found a lot of files in the application-directory of GuitarPro.
The MIDI-Note-Number is included in the files.
So, If You own GuitarPro, then check the folder of GP and You will find a lot of very authentic samples Instruments.
I found a lot of guitars, sax, piano and a lot of other samples.
They are sampled in different Velocity-Values.
I had not tested specially with samplerbox if thy work but as the Filenames look quite good to create a good Samplerbox-Instrument out of these samples.
based on the Copyright it is forbidden to make the samples public. Probably someone creates the Configfiles for Samplerbox for these samples and share these configfiles.