I have Manjaro Linux installed on a 27" iMac and pipewire came preinstalled. In /proc/asound/card0/codec#0 it says pretty much all commonly used sampling rates and depths are supported:


However, when I play any "HD" audio files obtained from eclassical.com and nativedsd.com (96KHz/24bit, 192KHz/24bit) they're resampled to 48KHz. This is with nothing in ~/.config/pipewire/pipewire.conf.d and I checked that there was nothing in /etc/pipwire/pipewire.conf.d either.

I am determining the sampling rate during playback from looking at /proc/asound/card0/pcmp0/sub0/hw_params while sound is playing: it always says 48KHz.

If I make a file ~/.config/pipewire/pipewire.conf.d/10-rates.conf per the pipewire documentation:
and restart the pipewire service, sound players seem to work without error but there is no sound at all for files 48KHz and above. CD rips (44100/16bit) play fine and are not resampled to 48KHz. /proc/asound/card0/pcmp0/sub0/hw_params says the correct rate for 96 and 192kHz files but there is no sound while the player thinks its playing. I tried VLC, mpv, and pw-play players and all behave the same way.

I have also examined the FLAC files using spek (it's in AUR, but really ought to be included in the distro) to make sure they are really 96KHz/24bit and 192KHz/24bit.

I'm beginning to suspect CS4206 does not really support rates higher than 48KHz, pipewire has a bug, or there is a problem with the kernel sound drivers. I mean, almost no one likes classical music or jazz--what is typically recorded at these higher rates--so maybe no one bothered to check whether these rates actually work?

To me, there'd be a question of software, and hardware. You need to know that the original ISA bus ran at 7.86(?)MHz and through some labyrinthine and convoluted reasoning involving sample rates 44100khz was chosen as the max sample rate.

A lot of stuff got set up around that, and it kept downloads small. I would chase data on the chip, that "Cirrus Logic CS4206." What sampling rates does that handle?

IME, most internal devices in PCs have 44 or 48 khz sample rates, although usb sound cards go much higher (192khz). I can't talk definitely about Macs. It could be that the software will do 192khz, but the hardware won't.

Well, it appears Cirrus Logic doesn't really make a 4206?! The closest match is 4207 and the rumormill says 4206 is 4207 but somehow customized for Apple. I give up. Plugging in my USB DAC....

What's the sampling rate on the CS4207?

BTW, a lower number strongly implies lesser features, not more. So a CS4207 modified for Apple might be CS4207<letters>. Is there a CS4205? It's most likely to be a testing thing if the rumour mill is right. E.g. lower sampling rate.

You see this most often with CPUs. I have a Ryzen 5 5600. There is a Ryzen 5 5600X with 100MHz extra frequency and 300MHz extra on turbo, which sells for €100 extra. But many parts that fail the 5600X spec actually pass the 5600 spec. So they are sold as 5600s.

You can read the specs (pronounced "marketing info") at Cirrus Logic; it appears to support 44.1 to 192kHz with depths 16,32 bits.

I'm thinking maybe 4206 in iMac is just 48kHz. Or that's all the generic kernel sound drivers support? Anyway, I really have given up on this: the reward is too little for way too much wading into the ever-shifting sands of ~/.config.

It's curious that pipewire has so many debugging tools: pw-cat, pw-cli, pw-top, pw-dump etc.... Bet it "just working" properly is a rare thing.

In a fit of disgust with the ongoing Linux Sound Server mess, I decided to try FreeBSD on this system. (FreeBSD still uses ye olde OSS.) Unfortunately, it works, but the sound quality is horrible and no one knows why. iMac 2011 with CS4206 has been discussed on several BSD forums (not just by me begging for help) with no conclusion reached. Maybe Apple broke 4207 in some secret way so it only works 100 percent properly with Mac OS. No, I'm not installing whatever last bloaty, horrible old version OS X worked on iMac 2011 just to test, LOL.

Apple have a policy of not being give-ish about hardware details or software. They don't ever want competition.

That said, most things do quite well on 44khz/48khz When you consider that the highest note any soprano can sing is about 9khz that puts things in perspective. 'A' above middle C is 440Hz. One octave up is 880hz; another octave up 'A' is 1,760Hz. What you want to hear is actually well covered.

The Hi-Fi cards that do 192khz will have higher quality throughout, and produce lower THD, TID, etc distortion rates. Speakers often contribute significantly to the total distortion. So do capacitors.

If your 13 year old iMac sounds lousy on everybody's software, consider hardware problems.