You may have noticed on the V803 that the WARM and QTUBE voicings only go to a max of 500 watts on a 4 ohm load, as opposed to MODERN's 800 watts.
Upon first glance, you might suspect that the output on these voicings are going to be less powerful than the MODERN voicing. But this isn't necessarily the case.
The MODERN is a traditional solid state-type bass amp, while the WARM and QTUBE have a tube-like output. This means that the 500 watts of WARM and QTUBE match the wattage of a tube bass amp, whereas the the MODERN is 800 solid state watts.
You will actually find that the 500 tube watts will feel similar to the 800 watts of solid state in terms of volume and sounds just as big. So there should be no concern over being heard!