I dont think there are any problems hooking up the Virus directly to your active monitors......Although I would double check that fact.
If you had a patch bay, you could simply 'patch' your Virus outputs to your monitors when you dont want to turn on the PC
Patchbays are relatively cheap these days....cheaper than a mixer, but it may be handy to have a small mixer to monitor your outboard synths. Check out the
Mackie 1202VLZ....cool little mixer
How exciting....setting up your studio! I remember the day well.....
Have fun!