After digging around a bit, these sites offer free .flac (lossless) music, the first link even offers free movies, books, software & images too:
https://archive.org Just search for FLAC, click the audio file you want to save. Find 'Download options' & download the music file.
http://www.2l.no This is one of the best free lossless music download sites. It provides free hi-res music files that are available in DXD, DSD64, DSD128, DSD 256, MQA, ETC. Visit the 2L website and click HiRes Test Bench. Then you can download hi-res music for free without registration required.