The Virus understands the number of voices to be 100.
They are reduced during Unison Mode (Common Menu) which can therefore divide this number of voices by 8. In addition, Analog 1-4 pole (Menu Filter): reduces polyphony by 50% Also, WavePWM or Grain / Formant Complex ( Menu Osc1/2 Menu): reduces polyphony by 50%.
SOLUTION =
Prepare a PATCH 00 to "eat" voices using Unison on 8 voices + Analog 1-4 pole (Menu Filter) + WavePWM or Grain / Formant Complex (Menu Osc1/2 Menu)
In MULTI mode, in Track 1, put your VINTAGE PATCH
Then, put this PATCH 00, in Track 2, in Track 3, in Track 4, etc… stuck on the same channel each time. Accumulate this "PATCH 00" several times until you manage to eat 96 Voices. EDIT : track 2 to 3 and more... = Volume on "0" and "Part enable" = ON
NOTE: Not tested, this is just an idea…