Given that your needs are simple, maybe there is a better "place" to spend on improvements. What do you record with a mic(don't say "vocals", say "metal screaming vocals, or soft jazz vocals, male or female"...you get the idea), AND, how are the acoustics of your room? And finally, what do you have right now for microphones? The Mbox 3 preamp is pretty darn clean and linear, so maybe what you really need is a better mic and/or a better acoustic space to record in
(sometimes a bad case of GAS can over-ride sensible choices
)
GAS=Gear Acquisition Syndrome
