Cool, then looking down the usb route the
Focusrite Saffire 6 USB and
Presonus Audiobox 22VSL would both do what you need them to. however, in real terms, the quality
may be little or no better than
the fast track pro in some aspects. If we say you're current needs/issues with the fasttrack pro is the preamps and software monitoring latency then the mic preamps on both the focusrite and presonus sound great and, to my ears, better than the maudio AI's i've used (fasttrack ultra and
the fasttrack MKii) and, looking at the specs, the latency should be lower (i don't do much, if any, virtual instrument stuff so i'm basing this just off the spec sheets with a pinch of salt) At this price point though all the products are relatively comparable. Would firewire make a difference?; well, maybe, or at least it opens up more avenues, and there was certainly a time when firewire swept the floor with USB stuff, but not so much anymore. However, the firewire based
Focusrite Saffire range are excellent boxes. Otherwire, and imo something that seems ideal in this situation, i'd say you're best bet may be something like the new
Motu Track16, although i have no idea of the US$ price (it's about £450 over here, soooo $600 maybe? IDK). The preamps on the motu stuff sound great, the converters sound great, and it's also both USB and firewire with the only difference being that when it's plugged in with USB you need to plug it in to an external power plug, whereas in firewire mode it can be buss powered.
The other things worth thinking about are; does
maschine have midi in? if so, have you tried it to see if the latency is better than going through the fasttrack pro? Also, if it's an issue with the preamps for the mic then it may be worth looking at interfaces with line level inputs and look at a separate higher quality preamp such as the
GAP Pre-73