JackD is a low latency audio mixing framework, kind of like a mixing desk for audio applications. It's not a hardware interface but does itself use ALSA etc
It's a kicker because I actually wrote full Jack headers for pascal last year and then lost them when decided to try a new linux distro one day. (they're actually tiny, only took a day or two)
ALSA as far as I'm currently aware has pascal headers in the form of ALSAPAS. They've not been update for a while so you may find some more exotic functionality missing (perhaps with midi etc) but the basic functionality - Audio Buffer cycle etc should be fine.
You're highly unlikely to get ASIO like performance or anywhere near on a raspberry PI. It does however depend on many factors, primary in your case will be the audio chip the PI comes with. inbetween you and the sound-card there are a number of buffers, your apps, ALSA, the hardware etc.
The final latency being a combination of these three, you might have a limit you can't change or you might find that the CPU simply can't process the audio frames quickly enough.
ASIO (to my current limited understanding) is capable of such low latency because A) you're writing directly into the hardware buffer or as close as the drivers will let you B) is set up in such a way that you're writing new data on a knife edge with no OS imposed delays etc note that ALSA, WaveOut, DirectSound etc are designed to provide smooth audio output on a wide range of performance profiles where as ASIO is studio-grade stuff that assumes a fairly quick CPU.
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All that said it still may be possible, but I should imagine it's going to be some hardcore direct interface with the sound chip or some special ALSA/Kernel functionality I'm not aware of.
The PI is a popular piece of kit, I should imagine that audio-processing is being pursued by many people so you're definitive answer one way or the other is probably out there by now.
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