Hello Takehisa,
I have not looked into the I2S bus before, so I pulled down the standard and had a look.
As you point out this standard is written around TTL logic levels. Our first generation isolators ADuM130x, ADuM131x, ADuM140x, ADuM141x use TTL logic levels for their I/O buffers, and should be compatible with your application. Our newer products use CMOS logic, but for an audio application, their performance should be very adequate.
Was there a specific performance goal you are considering the parts listed in your inquiry?
Best Regards,
MSCantrell