Usenet and BitTorrent are probably the best two sources of lossless encoded music.
For BitTorrent, try thepiratebay.org. Despite the website being well known for getting trouble with the entertainment industries, some artists have already shared their work via BitTorrent intentionally to get their music heard. For example, one artist “Lamont” shared their album “Golden Daze” in MP3, FLAC and OGG formats back late 2007 to promote their music and achieved a whopping 100,000 downloads as a result.
While Usenet is also a pretty good source for FLAC lossless encoded music, you will likely need to purchase a subscription to a good Usenet provider to download any, unless your ISP provides access to the binary newsgroups. The website binsearch.info is a pretty good search Usenet search engine if you’d like to see what is available on Usenet.
When you try these two or some other P2P client, try searching for the artist or song name including the keyword “FLAC” or “APE”. Your playback software will also need to handle these formats to play the music. For example, while Foobar supports “FLAC”, you’ll need to download Monkey’s Audio decoding support to play “APE” lossless encoded files.