From experience this is an easy one for me... I had an MBOX1 which as you well know isn't state of the art any more. I have never really been able to get a good sound out of it, so I naturally assumed it was my MIC so I upgraded to an AKGC4000. I thought it was still rubbish and bought the wrong mic so I bought an AKG C414 now by any means they are not rubbish Mic's. But it still sounded like most of the frequencies were missing, so I decided I'm going to change everything. First thing was the pre-amps, so I bought a Focusrite sapphire and my god all of a sudden it sounded fantastic. Had others Burrman and tried a Profire 2626 and I was so releived at the improvement and when I sang it sounded like me YAY!! Pre-amps make all the diff.