Rightly or wrongly, I want to be able to transcribe vinyl and tape with an initial bit-depth of 24 bits, so as to provide as much headroom as possible for any subsequent processing to get its teeth into before I convert to 16-bit final form. On Win7 both MME and Direct Sound truncate to 16 bits. So I turn to ASIO. I want to congratulate whoever wrote the instructions on how to create an ASIO-enabled version of Audacity, because for me following those instructions produced a working ASIO-enabled version at the very first attempt.
Now for the issues. First, what I think is an Audacity issue, which is that in the setting up of devices I see only an entire ASIO device listed for either input or output, whereas I would expect to see each separate input or output (as the case may be), probably with the inpute offered as L/R, L and R. So for my M-Audio Delta Audiophile 2496 card I would expect nine choices of input device (Line, SPDIF and Mixer, each ×3), and this is what I get with Sound Forge Audio Studio. But with Audacity I only get the one. The good news is that it does pick up the incoming digitised signal from the line inputs, and examination of the exported but unedited 24-bit WAV file shows that I do have 24 bits of data there (how much of that is garbage is another matter, of course) whereas doing this with MME or Direct Sound gives 16 bits padded with zeroes. On the output side, I am getting line output, have not checked whether there is SPDIF output as well. So the first question is why am I not seeing the full range of inputs and outputs?
The second issue seems to me to be more likley a driver issue with another device, an M-Audio Audiophile USB. With this device, attempting to start recording (with only the line input to the device enabled) causes Audacity to complain of a mismatch between sample rates even when they are set the same. This does not happen with SFAS, which records quite happily from this device. A possible explanation is that Audacity is interrogating the device and not getting a sensible answer, whereas SFAS isn’t asking the question. If that is right, then the M-Audio ASIO driver would seem to be the problem. The device works fine via MME or Direct Sound – but then, of course, I am limited to 16 bits.
So why not just use SFAS? Well, I am using a trial version for these tests, and there are two reasons why I would not particularly wish to spend the modest amount of money for a licensed copy. First, like some other Sony software, it does not provide software pass-through to allow listening during recording. The 2496 has a hardware mixer that allows monitoring, the USB does not. Secondly, it does not allow different devices for input and output, and I would like to be able to use the USB for input only and listen through the 2496.