The benefits for me are:
-Double the power, which is useful for harder to drive headphones.
-Easy buttons operations which allows you to change pretty much everything and is specially useful to switch between EQ profiles.
-The sourround processing is very noticiable with multichannel content (games, movies, series etc). It's more immersive and the sound positioning is improved. I don't know if it's noticiable with IEMs, as only use full size open back headphones.
The surround effects are not meant to be used with stereo music, this isn't a device to do that. You won't notice any difference when playing stereo music. It just sounds like a good and transparent DAC/AMP. If you bought this device only to listen to music with IEMs, you rather send it back or sell it and buy a Qudelix 5k or similar.