Interesting the VB's sound hardware is so close to the PCE's. 6-bit wavetables would be nice, less stair-stepping of the waveform. Anybody know how many bytes of RAM each wavetable can use? If it's 64 bytes, that should make a nice, square 64x64 sample grid to work with.
The official docs are out-there if you look for them.
It's 32 6-bit-samples per-wavetable, and there are a total of 5 wavetables, but each channel can independently select which one of the 5 wavetables it is going to use (i.e. they're not tied to each channel, unlike the PCE).
Channel 6, and only channel 6, is able to output noise ... but it is a noise-only channel and no wavetable possible.
According to the doc, there is no direct sample-output, and you can only change the wavetable memory when ALL sound output is stopped.
So ... very limited compared to the PCE.