I have tried using the TI fx with external sounds - doesnt work as well... not sure why. The main fx on the virus ti (reverb, delay, chorus and phaser) are very good for a synth, but i think the reason they seem so good is because they perfectly suit the rest of the synth - gel perfectly with its character etc.
Ive tried using them on pianos and other synths - just didnt even come to other reverb processors nor the VST that TGND mentions. I mean they aint bad and it depends what you after as well - a digital dry plate with artificial color - ie typical reverbs used in trace, or something you can subtley add to other sounds. If the former - then they aint bad, but still dont come close to even relatively cheap good hardware fx - TC Electronic stuff for eg, or Lexicons (but not MPX200/400 which are brand exploits).
If you have a v-synth handy - that actually has quite a decent fx unit inside it as well... again same thing - seems to sound amazing within the v-synth but doesnt seem to translate well to other sources.
TGND - my idea of an analog reverb is a plate (metal, glass, concrete etc), springlines etc or massively parellel bucket brigade delays etc - not any kind of digital processing - of those glass room reverbs sound lovely on synths
Oh - one thing that is nice with the TI - if your input patch outputs to pair 2, then feed the result back in again mixed with the original input sound, and use reverb + delay (the reverb is there to just smeer and futher color the delay) then you can do quite a decent sync tape delay simulation - somehow the virus sound character seems to suit that kind of abuse quite well - add a little subtle modulation to the delay.
Of course the DAW+USB bound folks probably never discover stuff like that
TGND m8 - abuse those analog ins/outs - way more fun