DSF is audio file format (.dsf file extension) contained lossless 1-bit audio stream under delta sigma modulation (famous as DSD). It is audiophile high resolution file format for 1-bit DSD DACs.
Open DSF audio files possible with audio players:
1. Foobar2000 (with sacd input plugin)
HD audio converter for DSF file format AuI ConverteR 48x44
(full DSF support in version PROduce-RD)
change sample rate and gain, convert to/from WAV, FLAC, AIFF, DSF...
Audio players can playback DSF files as directly to 1-bit DSD DAC or convert inline ("on fly") to PCM and playback at traditional PCM DAC.
Audio conversion PCM to DSD and DSD to PCM has loosing quality anyway.
Alternative way offline (non-realtime) conversion DSF to PCM or PCM to DSF with converter software. Usually offline conversion is not restricted by real-time CPU performance and can use "heavy" precise algorithms.