There's some pretty obvious auto-tuning going on here with the vocals. That, and the bass guitar sounds kind of muffled. It doesn't have one key frequency range in the low end that it is resonating in. Occasionally on certain notes I hear it generate some 200hz mud, but it doesn't have a strong and consistent low end.
With the vocals, Go through and listen and automate the autotune only for the parts where he really needs it. Right now he kind of sounds robotic, and you can hear the pitch shifting kick in between certain notes.
As for the bass guitar, this is hard to get right without quality monitors. Generally I listen all the way through the bass track and listen for certain notes that are louder than others. Most of the time with bass, there will be one or two notes that are consistently louder/more rumbly than the others. Isolate one of these notes, solo the bass guitar, and do an EQ sweep through your low end to find the offending frequency and then do a notch cut of it. Basically, that means taking a very narrow bandwidth, do a massive boost, and sweet it slowly through the frequency range, listening for when your EQ boost has come accross the frequency that is generating the noise. You'll be able to tell by how loud it sounds once its on the right frequency. Than just turn the boost into a -5, -6 db cut.
Once you have that frequency notched out, then it's safe to give the bass a general boost in the low end. Usually it's around 90hz - 100hz.