There are a couple of audio interfaces that have the potential. UA interfaces have DSP chips that can run (sort of) general purpose stuff that could be leverage

There are a couple of audio interfaces that have the potential. UA interfaces have DSP chips that can run (sort of) general purpose stuff that could be leveraged by Max/MSP if the SDK were open (it may be, I haven't looked). Also, RME interfaces often have an FPGA in them which I've often thought would be a useful co-processor for audio, but I'm pretty sure that they aren't user programmable either. Basically, the hardware has been around for ages, but the software is non existent/limited due to the vendors not fully realising the potential of the hardware, and reverse engineering this stuff is really hard!