Bug#644901: Additional information

[Andreas Glaeser]

In the meantime I managed to build newer alsa modules on my system:
/proc/asound/version :
Advanced Linux Sound Architecture Driver Version 1.0.23.
Compiled on Dec 28 2011 for kernel 2.6.32-5-amd64 (SMP).

the souncard was replaced, too:

/proc/asound/cards :
 0 [SB             ]: HDA-Intel - HDA ATI SB
                      HDA ATI SB at 0xfe8f0000 irq 16
 1 [CA0106         ]: CA0106 - CA0106
                      X-Fi Extreme Audio [SBxxxx] at 0xe800 irq 21

03:06.0 Multimedia audio controller: Creative Labs CA0106 Soundblaster
	Subsystem: Creative Labs Soundblaster X-Fi Xtreme Audio
	Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping-
SERR+ FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 64 (500ns min, 5000ns max)
	Interrupt: pin A routed to IRQ 21
	Region 0: I/O ports at e800 [size=32]
	Capabilities: <access denied>
	Kernel driver in use: CA0106

But this did not solve the problem. The crackling sounds are still there. They are less
obstrusive when the two-pass equalizer is left off, but do not completely vanish.
When the bass is cranked up too much, this effect even appears slightly with the onboard
soundcard:

00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA)
	Subsystem: Biostar Microtech Int'l Corp Device 821f
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping-
SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=slow >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 64, Cache Line Size: 64 bytes
	Interrupt: pin ? routed to IRQ 16
	Region 0: Memory at fe8f0000 (64-bit, non-prefetchable) [size=16K]
	Capabilities: <access denied>
	Kernel driver in use: HDA Intel