Do you mean 600, or 600E?  IIRC on 600E there is a pci audio device
that isn't supported and if you use it in soundblaster emulation it
works fine.  On a 600 (2645-41U) with GENERIC_LAPTOP:

  sb0 at isa0 port 0x220-0x237 irq 5 drq 1: dsp v3.02
  audio0 at sb0: half duplex, mmap, independent
  midi0 at sb0: SB MIDI UART (CPU-intensive output)
  opl0 at sb0: model OPL3
  midi1 at opl0: SB Yamaha OPL3 (CPU-intensive output)

But I haven't tried audio - this is a basement router.

On a 600E (2645-4AU), I get:

Cirrus Logic CS4610 SoundFusion Audio Accelerator (audio multimedia, revision 0x01) at pci0 dev 6 function 0 not configured

I had this computer working under FreeBSD 4 long ago; it sounded fine
and the chip is definitely not 1 bit.

-- 
    Greg Troxel <gdt@ir.bbn.com>