Ok, here's the thing... your GT55
is a condenser mic and as such, it requires phantom power to operate. The Fasttrack is a usb audio interface that accepts dynamic mics (shure sm57
, sm58); dynamics don't need phantom power.
As such, you need a mic preamp with phantom power. Presonus and ART make a good, affordable preamps (there are myriads of mic pre's out there). I use the ART TubeMP
V3 with my MXL V63M so I can get that tube sound.
Search the net for mic pre's with phantom power, and when you decide to get one, bring along your mic so you can audition the preamp.
Hope this helps!