virus vs duet: audio interface?

[myfilthyheart]

anyone use the audio inputs on the duet much? i have a little phatty, and i dont want to castrate any of its "phatness" by using a sub-par audio interface. ive been considering getting an apogee duet.. but i wonder, do i really need one? what is everyones experience with using the virus to record into DAW's? would there be any point in getting another interface? is the sound quality as good as i would imagine?

another question.. if i am using my virus as my sound card.. can i leave it on, all the time? i know i could do that with a duet, but i feel uncomfortable leaving my virus desktop TI powered up and running 24/7.