Hi Jeff:

It's a reasonable question, and unequivocally, there is no difference ... zilch... in 32 and 64-bit OS sound quality.

What the 64-bits refers to is the memory fetch size -- when the CPU (the computing chip) makes a call to random access memory (RAM ...these are the vertical cards on your motherboard ... see the picture of my motherboard below ... the RAM is up front and to the left... the CPU is under the fan) it brings back 64-bits (twice as much as with a 32-bit OS). Since these fetch operations are on a clock (e.g., my x*3.5 billion fetches a second for my computer where the x* is the CPU to clock multiplier) you technically could do twice as much computing with a 64-bit OS.

You have to have a 64-bit CPU chipset to use the 64-bit OS; 64-bit OS give you access to more than 4GB of RAM (your upper limit with 32-bit computing ... 4GB is what I have in the computer shown below)

But, when it comes to an application like BiaB ... 64 and 32-bit OS are processing exactly the same information ... the same stream of digital 1s and 0s for audio DAC and output on the audio board, at exactly the same time and the sound output is identical.

Also, I have found from a practical standpoint, there is very little speedup in going from 32 to 64 bit Windows. I have a dual boot on the machine below and both 32 and 64 bit Win 7 have computation performance of 7.4 and memory fetch performance of 7.3 on the Windows Performance metric (right click on 'Start/Computer' and go from there to compute your performance ... 7.9 is tops).

I think adding cores is a lot cheaper and better way to improve performance. My four core AMD Phenom II is running about 3 times the number of instructions of a single core on the AMD chip ... see my other post (click here) for how I did this on the cheap )

Chris