OK, here's the Green Day(?) update. Tests have confirmed snap, crackle and pop correction by about 80%. A shout out needs to go to some obscure post on a Native Instruments forum, coupled with a Linux forum!
 
We know the sound crackles are caused by the nVidia card operating in PCIe v1.1 mode. We must force the card to remain in PCIe v2.0 mode, but how? It's a thing called PowerMizer, and as far as I know, it isn't possible to tweak using accessible controls or power options. Instead we must go into... the... Registry!
 
WARNING: Registry hacks are needed. Proceed at your own risk and backup the registry before you do it.
 
The goal is to disable the PowerMizer function. One would think this is only something that is used on a laptop, but rest assured, I am on a desktop (er, rather floortop) PC!
 
The following is summarized and edited from the Native Instrument's forum:
 
1. Open up Regedit and go to:
\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\$$$$$$\0000\
The $$$$ symbols will be random numbers, particular to your machine. Note there will be a few of them.  So open each one and pick the "0000" folder with the most keys in it.
 
2. Right-click within said "0000" folder and create new DWORD 32-Bit keys as listed below.
NOTE: It's best to name them accordingly as they're created.
PerfLevelSrc
PowerMizerEnable
PowermizerLevel
PowermizerLevelAC
 
3. After all have been created, double-click each one to open it.  Edit the Value data to the appropriate value listed below:
PerfLevelSrc to 3322
PowerMizerEnable to 0
PowermizerLevel to 1
PowermizerLevelAC to 1
 
4. Reboot and PowerMizer will be disabled! Verify your nVidia card remains in PCIe v2.0 mode by using the GPU-Z utility.  Test to see if crackles and pops are lessened.  Also check to see if you can squeeze out a better latency with your audio interface.
 
With this tweak, I reduced the snaps, crackles and pops by about 80% (best guess). They are still there, but very very minor compared to what it was. As for latency improvements, I am now down to 5.0ms with it being about 90% stable; about what it was before the tweaks...now just faster! More stability tests required.
 
The GTX670 runs cool and quiet; there is no fan speed increase. GPU clock is running not at full speed, but rather at 81% of rated. Memory clock, however, is at full-rated speed. Power consumption is reported as +10% over stock. Please note, that the card still runs "adaptively," meaning if a 3D application is loaded, then the card will ramp up to full potential. This is probably why the snaps, crackles and pops are only reduced about 80%.
 
Try it! See what happens!
 
More information (http://forums.opensuse.org/english/get-technical-help-here/hardware/410089-nvidia-powermizer-how-tweak.html):
PowerMizerEnable=___ = to switch it on or off (using hex codes)
PerfLevelSrc=#### = performance strategy where "22" is the code for fixed frequency and "33" for adaptive frequency, defined for battery and AC use.  Example, 3322.
PowerMizerDefault=___ = code to enable a performance level for battery use from 1 to 3, being from high (1) to low (3) performance.
PowerMizerDefault=___ = same as above but for AC power.
 
I suppose I could have made the PerfLevelSrc code "2222" instead of "3322" to force the card into fixed frequency no matter what it thinks it's powered by. I may try this. If it improves the numbers, I will revise.