That would need isochronous transfers which is currently only supported by the Deneb, so perhaps if you're running MorphOS PowerUp.
No, I only use MorphOS 2.x on my Efika, since I don't have any PowerAmiga...
So there's no way it can work at all?
Can you explain why only Deneb supports this? I missed this information somehow.
One of the unique selling propositions of the Deneb is the cheap access and use of USB soundcards on Amiga Classic Machines, where the users would have to spend >100 EUR for a Zorro or clockport soundcard instead. On Pegasos you have onboard sound, hence there is not much of commercial sense to put a lot of work and effort into implementing iso transfers for the lowlevel driver that would only be necessary for this special use case of USB audio on the Peg. There is no technical limitation that would inhibit the implementation for pciusb.device.