Provided you don't have the audiophile version transfer is OK. But according to PGMusic if you have the audiophile version on an external disc drive and transfer to your comp drive the WAV tracks get copied to WMA - (Windows Media Format i.e somewhat compressed).
Re.
Frank, I can tell you that in my case this advice is just not true. I have the audiophile version, and for many years I have copied selected RealTracks to a separate internal SSD drive. As Noel mentioned, this isn't enough - you also have to copy ST2 and XT2 files to the /BB folder. The process is complicated and I don't recommend it for the faint of heart, but it can be copied manually and it will work. Could you please cite the source of this advice from PG Music? I have to believe the context is not correct (unless they, like me, were just trying to discourage you).
Matt you asked for a citation. From the read.me files on my PGMusic audiophile ext drives for 2015 and 2016.
BIAB 2016
"Option #3 - Install Band-in-a-Box© AND RealTracks on your computer hard drive (**about 100 GB free disk space required**)
In addition to everything installed by Option 2, this will copy the RealTracks and RealDrums folders from the USB drive to your computer's hard drive, as if you had installed everything from DVD. This will allow you to keep the PG Music hard drive primarily for backup, and use Band-in-a-Box© and RealBand (along with the RealTracks) directly from your computer hard drive.
Since these folders contain many audio files, this option requires much more hard disk space, and may take about an hour to complete depending on how fast your computer is.
Note that this will NOT copy the .WAV files, only the .WMA files, as explained above ("Important information about this AudioPhile Edition").
BIAB 2015
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Important information about this AudioPhile Edition
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In this AudioPhile edition hard drive, we have included all of the original uncompressed "lossless" audio files (*.WAV) for RealTracks and RealDrums, in addition to the compressed ("lossy") *.WMA files that we normally ship.
Note that Installation Option #3 described below will only copy the compressed audio files to your computer's hard drive, not the .WAV files. While not required, if you wanted to copy all the .WAVs to your computer hard drive as well, you would choose installation Option #2 instead, and then manually copy the Drums and RealTracks folders from the bb folder on this USB drive, to the bb folder on your computer hard drive. This would usually not be practical, since it would require almost 850 MB of hard disk space.
You shouldn't delete the WAV files from this hard drive, since these are the original uncompressed files (higher quality), and this is one of the advantages to having the AudioPhile hard drive. Note that if you DO delete or archive the WAV files leaving only the WMA files, it is possible to uncompress them back to WAV, however these new files will not be the same as the originals because they will have already been compressed once - that is, they will be lossy."
Cheers F