1) To send note data to the MPC from your Virus:- connect Virus TI MIDI Out into MPC Midi In, and make sure they're set to the same MIDI channel
2) To send the MPC audio output to Virus:- connect MPC audio outs into Virus TI audio inputs
3) To enable audio-in on Virus TI: choose one of the initialised patches (usually called -START- or -Init-), then select from the menu: "Edit > Common > Input Mode > Off/Static/Dynamic"
To enable audio in, you'll want to choose either Static or Dynamic from the above. If you want to use the Virus as a conventional effects box choose Static. If you want to also gate the incoming audio using the Virus keyboard, which brings the Virus Amp/Filter envelopes, LFOs and other modulators into play effectively treating the audio-ins as oscillators, choose Dynamic. For more info on Static vs Dynamic:
http://www.infekted.org/virus/showth...939#post302939
Once enabled (in Static or Dynamic mode), to the right of the Input Mode you can select which audio inputs you wish to inject into the Virus.
Now you can play the MPC from the Virus and have the MPC outputs go to the Virus effects and add whatever you want to the input. You can also use the standard Virus filters, resonance on the audio input too, and even use LFOs and stuff to modulate these. In the case of Dynamic mode, you'll want to edit the Virus Amp EGs, et al, as this will effectively add a second layer of envelopes in series after the ones on the MPC themselves.
To use a full stereo signal, make sure oscillator Unison = 2 voices. This enables the required two voices of polyphony to process both inputs.