Is there any DAC compatible with FreeBSD?

I've been listening to the dual PCM56 DAC for a couple of weeks now using the setup shown in my last photo, and I can highly recommend it, I'm amazed how good it sounds at the low price. I bought a couple of spares since they are so cheap! I think there may be a burn-in effect, it seems to sound even better after a couple of weeks playing. I think the passive low-pass filter they have implemented works well. Surprisingly, I think it sounds better than the WM8740 I tested earlier. Somehow, the R2R dac sounds more 'analog'. For a low cost system, this is very nice IMHO. Of course the headphone amp, SMSL PO100 and linear PSU get the most out of the two PCM56 chips; I'm sure any other good quality headphone amp, would work just as well. But the real magic lies inside the Burr-Brown PCM56 chips themselves. Very easy, fatigue free listening, very musical. This was tested using DT-990 PRO headphones.

I've got an SU-1 on order to try out one of the AK chips, but I'm really pleased with this small BB NOS dac.
 
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Alain De Vos said:
I use a general USB scarlet 8i6 focusrite. It works out of the box in Linux, no need for any driver, i.e. usbaudio & alsa.
Could not get it to work in Freebsd.
As long as there is no "qasmixer" application or alternative mixer detecting all channels many will not work ...

ardour5/jack didn't worked neither with my usb-dac.
Click to expand...
I successfully used a Focusrite Scarlett 2i2 with FreeBSD, with no drivers. But it only has two channels. I have read other places that more channels are a problem.
 
This is only obliquely connected to audio, but I thought it was interesting. The video looks at some thin film laser-trimmed resistor networks, and discusses some details about how they work and how the laser trimming is done. Interesting because chips like the Burr-Brown PCM56 DAC (and others in that series) have an internal laser-trimmed NiCr R2R resistor ladder, which I expect was made using similar techniques to those shown in the video. In the PCM56 the ladder must be physically much smaller than here since the whole chip has to fit into a standard 16-pin DIP package. It also makes me think that as the number of bits increases, the thin-film R2R network will increase in size and also cost, and that is likely to be one of the motivations for the changeover in the industry to delta-sigma designs for chips beyond 16-bits. It's quite interesting to see how these things work under the covers.
View: https://www.youtube.com/watch?v=Rxy-VpSDPg4

I think chips like the PCM56 must have been quite expensive to manufacture (and buy) when they were originally launched, especially if the R2R network in each chip was laser trimmed under some kind of active testing process, as he describes; the PCMC56 datasheet does mention that the R2R ladder was laser trimmed. Presumably being able to buy these now at low prices is really only possible because they are effectively "surplus stock" that has been sold off cheap to the highest bidder for disposal. Of course this chip would be considered obsolete today in the age of 24-bit streaming hi-def audio, being only a 16-bit dac, and you can't use it in small devices like smartphones because the thru-hole 14-DIP package is far too large. It's kind of interesting that digikey still has a decent number of them on the shelf, although they say its out of production.
 
Multi-channel as such is no problem, works for me:
Code: 
uaudio0 on uhub4
uaudio0: <Icon Global 32Ci4, class 0/0, rev 2.00/1.00, addr 2> on usbus3
uvideo0: 2 format(s), iface_index=1, endpoint=0x81, psize=3060, isoc
uvideo0: default format: pixfmt=0x47504a4d, 1280x720, max_fbuf=1843200
uvideo0: UVC camera on /dev/video2
uaudio0: Play[0]: 192000 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer. (selected)
uaudio0: Play[0]: 176400 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 96000 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 88200 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 48000 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 44100 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 192000 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer. (selected)
uaudio0: Record[0]: 176400 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 96000 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 88200 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 48000 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 44100 Hz, 14 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: MIDI sequencer.
pcm5 on uaudio0
uaudio0: No HID volume keys found.

Whether specific models like the 8-channel scarlett work I don't know.
 
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