You can read about the volume options in the
wiki. I prefer internal volume for several reasons:
1. It is the only one that works with ASIO output
2. It uses 64-bit processing for volume control that is dithered down to 24-bit or 32-bit for output - this is basically the highest quality you can get
3. You can use Volume Protection, Maximum Volume, Volume Reference Level, Loudness, and Startup Volume
4. You can maximize headroom for EQ without clipping
5. You have JRiver's built in clip protection
6. Possibly better control with external apps for Android or iOS
