I too find the sound in R3E to lack a certain something, something hard to explain, something growly something in the bottom end I think. Don't get me wrong, the sounds are amazing but there's still something lacking.
That said, here's a few things to think of;
In the game, set it to Stereo rather than surround or any other setting, and if there's such a setting make sure to set it to headphones rather than speakers (can't recall if there is atm).
Outside the game, turn off any fake surround processing, dolby headphones or other kind of settings that tamper with the sound to try make you believe that you're getting positional sound from 2 speakers, while it is in fact possible to get really good positional sound using only 2 speakers this is usually achieved better at the source rather than trying to fake it after the fact by destroying the sound using effects. These also tends to kill bass completely for me, for some reason, probably because the human ear has a hard time telling where low frequencies are coming from.