I'm using VMWare Workstation 7 and I've installed the Ensoniq Driver 1.02, but the audio output sound isn't very loud even at the highest volume.
I've discovered another way to resolve the low volume issue that works with Ensoniq 1.02. Add the following line to the VMX file
pciSound.emulateMixer = "FALSE"
This will make the guest use the maximum volume for the mixer output instead of emulating a mixer, and you'll get 12db higher output.
Another setting I found is
pciSound.enableVolumeControl = "FALSE"
which disables the volume control on the guest completely. You'll always get the maximum volume on the guest side, but you can still control the volume from the host.
In another bit of "good news", I figured out the cause for the stuttering audio
It's got to do with the way VMware emulates the ES137x, which makes it incompatible with Apple's audio architecture. Apple's audio architecture assumes that the sound card drains the output DMA buffer at a fairly fixed rate, which could fluctuate somewhat around the sample rate, but not too sharply. VMware's backend doesn't really "drain" the output buffer, but instead picks up the whole thing with "memcpy", and then passes it on to the host sound system from another DMA buffer which it prepares on the host side. VMware's emulation is technically permissible, but doesn't resemble anything like a real audio card. It works for Linux & Windows, because those OS's don't make any assumptions about the drain rate of the DMA buffer.
I'm trying to devise a workaround for this that doesn't require redesiging the whole driver. If it turns out that solving this requires a complete redesign I may drop it.
BTW, I think this issue would exist even if VMware emulated another chipset, but continued to drain the buffer the way they do. It's not specific to the ES137x.