Thanks to Marcin Jakubowski for submitting news about his new software tool called iqToSharp which is a simple tool that allows you to convert rtl_sdr IQ files into the SDR# IQ format. The rtl_sdr command line tool records raw IQ files but by default they are not compatible with the format used by SDR# so a conversion is required.
This is useful as for example you could set a command line script to record an entire band for a few hours on a portable Linux device like a Raspberry Pi, and then use the converter to listen to the file on SDRSharp at a later time. Recording the raw IQ file allows you to record all signals within the entire bandwidth at full quality.
Note that IQ files can become very large so for archiving compressing them with FLAC can be useful. You might also be interested in the SDR# FilePlayer plugin which allows you to easily skip back and forth in time through a recorded IQ file.