Description of problem:
subwoofer and centre channel speakers not working.

Version-Release number of selected component (if applicable):
Fedora 15 with all updates loaded.
Name        : kernel
Version     : 2.6.38.8
Release     : 32.fc15
Architecture: x86_64

How reproducible:
Every time.

Steps to Reproduce:
1. click sound icon on task bar
2. select Sound Settings
3. Hardware TAB, select "SB X-Fi" and select 5.1 output
4. select test speakers
  
Actual results:
No sound from subwoofer and centre channel speakers

Expected results:
Sound plays from subwoofer and centre channel speakers

Additional info:
# lspci -v
04:05.0 Multimedia audio controller: Creative Labs SB X-Fi
	Subsystem: Creative Labs Device 0031
	Flags: bus master, medium devsel, latency 32, IRQ 20
	I/O ports at c000 [size=32]
	Memory at fc000000 (64-bit, non-prefetchable) [size=2M]
	Memory at f8000000 (64-bit, non-prefetchable) [size=64M]
	Capabilities: [40] Power Management version 2
	Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
	Kernel driver in use: SB-XFi
	Kernel modules: snd-ctxfi