I'd prefer less conversions, and therefore less artefacts.
Exactly why you use the USB, no conversion what so ever...
To record the virus trough the analog outputs into my RME convertors
Why do you want to do this? it kind of contradicts this.
But what if i want to use my convertors instead of Virus TI Soundcard?
To record analogue from the Virus it would need to generate the sound. Or, do you mean instead of using the Virus as the designated sound card for the project. The Virus still needs to use its D/A if you want to record it the old fashioned way but It doesn't need to be set as the project Soundcard to do so.
if i had Virus TI Desktop it wouldn't be a problem.
There's no difference except one has a keyboard. (Edit: the Snow does have other differences. I'm comparing the TI keyboards to the TI desktop).
Due to the way you use your old equipment, i think the way the Virus TI does things has confused you a lil. In my set up, 2x Presonus Firestudios, Virus TI and other hardware, I use the midi ins and out on both Presonus AND, the midi ins and outs on the TI, as well as the USB to control the TI. All my hardware runs into both my Presonus, which is the soundcard for my projects. If i wanted to route from the TI audio outs it to the Presonus, to capture the 'characteristics' of the converters, it can be done, but i'm not the type to do this.
If you want to skip the characteristics of the Virus converters but only the RME fireface, you'd have to do that via a bounce and loop back. But, remember, non of your other hardware has the ability to skip their converters, unlike the Virus using the USB.