Can anyone recommend a good source for multichannel FLAC downloads please?

Many which come up during internet searches look less than kosher.

Also, what, if anything, prevents the purchaser cloning and sharing the download? Is there a digital watermark or one-time key? I am thinking about how I might archive such downloads.

In the spirit of Spinaltap, I would like to confirm that I am not involved in the corrupt theft of a global sport.