It is correct that the total bandwidth required for 128 tracks at 48 KHz is the same as 64 tracks at 96 KHz, which is the same as 32 tracks at 192 KHz. In the future we hope to be able to increase performance to 32 tracks @ 192k.Here is why:At the higher sample rates, there are some other issues related to the data transfer rate that come up, and they indirectly impact the PCI transfer rate. It's a bit complicated, but here's a quick summary...If you're using the 4-DSP Engine... at 48 KHz, each DSP must do 32 tracks for 128 total tracks. At 96 KHz, each DSP must handle 16 tracks for a total of 64 tracks. So, to reach 32 tracks at 192 KHz, each of the 4 DSP engines would have to do 8 tracks.That's where the issue exists: in the first release of the software (Pro Tools 5.3) we had to settle with "only" 6 tracks per DSP at 192 KHz. Even getting this level of performance was pretty tricky.Remember, our TDM systems use the sample rate clock to synchronize all the processing in the system. This is why TDM systems have very low latency -- we don't buffer a lot of data at various points in the processing chain. So, at 192 KHz, every 5 microseconds a "sample interrupt" happens on the TDM bus, and every DSP in the system processes another sample of data on the input side, and produces another sample worth of data on the output side (using the TDM bus to transfer the data between DSPs).So, as the sample rate increases, the amount of time between each sample interrupt decreases, which means that the DSPs have less time to do their work. This is why generally the number of plug-ins and the number of disk tracks are cut in half when the sample rate doubles.However, it's not always perfectly linear. The TDM Engine code in particular needs to do a lot of work to move audio data to/from the TDM bus and over PCI to host memory (to get to/from the disk drives). There's a balancing act that happens: the engine must spend enough time bursting PCI data such that a -6042 doesn't happen, but it must also service the I/O to the TDM bus otherwise another type of "data underflow" error will happen.So, to make a long story short, the balancing act gets really tough at 192 KHz, such that servicing 8 tracks worth of data per DSP at 192 KHz just didn't work. We had to settle with 6 tracks per DSP, which is why there's a 24-track maximum at 192 KHz.