Why do you have both the M-Box and the EMU 1820? Is it the 1820M with preamps?
You already have a decent mic. Personally I would unload the USB M-Box for some cash and stick with the EMU--it probably has better converters and no latency. Then I would buy a nice preamp. In the price range of a voicemaster pro you could get one of the UA Solos, a P-Solo, a Speck, a Sebatron.
