I am working on a playback/recording tool using the ASIO interface on a Win7 machine with 2 HDSPe MADI cards. I am implementing my own ASIO manager code (i.e. all the low level ASIO client calls to load drivers, create buffers, control I/O etc.). The application has a requirement to support 128 channels input and 64 channels output (and it might go up to 128 input and 128 output).

However, when I try to create the necessary buffers for ASIO I/O for 128 input and 64 output channels (i.e. 192 buffers in total), the ASIO call

ASIOcreateBuffers(pASIOBufferList, TotalChannels ,preferredBufferedSize, ASIOCallbackList)

where TotalChannels=192, preferred BufferSize=256, sample rate=48K and 16-bit sample size

is always returning the error ASE_InvalidParameter (it actually causes a BSOD once every 10 calls).

After further testing, I have discovered that the same code (with the same sample rate and size) is working fine for up to 64 inputs and 64 outputs (total of 128 channels) and nothing higher. So I would like to understand if there is a hardcoded limit for the number of channels/buffers you can create via your ASIO driver for the HDSPe cards or whether there might be another issue I am missing.

Other notes:
-    The PC is a pretty high-end quad-core machine with Win7
-    I have installed all the latest drivers from the website for the cards
-    Both the Hammerfall DSP settings GUI and mixer show the 2 cards and channel count/settings correctly
-    The ASIO calls to get the number of maximum number of input and output channels return 128 and 128 respectively so theoretically we should be able to go up to 256 total channels/buffers.
         ASIOgetChannels(&drvMaxInputChannel, &drvMaxOutputChannel)
-    The same code base has been used without problems on other ASIO cards/drivers for about a year now (although obviously for a smaller number of channels)