Mixer gain set up for virus desktop

[spectral_19]

I connected my desktop to a channel in my mixer. The mixer is a Mackie 1402 VLZ74. On the channel there is a switch marked +4/-10 that controls the sensitivity of the mixer. Which one should I use for the Virus desktop ???

I checked the manual and on page 9 it says "Make sure that the equipment you connect the Virus TI to matches the Virus’ requirements (+4dB Outputs etc.)".

This seems to confirm I should use the +4 switch position on the mixer channel. BTW what would happen if I set the mixer switch to -10 ?

Thanks !!