in theory you should be able to accomplish what you want to.
in actuallity it may come down to your computer components/drivers.
hardware synths are not zero latency...however they are a very usable latency of say under 15ms.
you should be able to keep your system latency around this.
my TI is working nicely with a DFI lanparty nf4 motherboard
and a creamware scope system.
ill caution you though by monitoring all by headphone...
this will make it an uphill battle to get a usable mix(as if it wasnt hard enouph)
and to much headphone use will damage your hearing.
