What are my options for 4-channel-or-more audio input devices in Ubuntu (or Linux in general)? I could deal with 16-bit input, but 32-bit is better, especially considering the amount of post-processing I tend to do.
I actually have one that has 4 inputs connectors, is the Intel DP35DP
And the same goes for my mother-in-law's PC. It has 2 PCI sound cards and the one that comes with the motherboard. Both PCI sound cards have more holes than a cheese from Tom & Jerry since you can connect (at least the first one I checked) 2 mics and has 4 more connections that am guessing only 2 of them are output (digital & analog). You can select which sound device to use in the "Choose a device for sound" either for input or output and then choose what specific connection for each.
Up to what I know the only cards or sound technology that was not supported 100% was the SB X-Fi Xtreme (Well the latest Sound Blaster Cards) but will be supported 100% in Ubuntu 11.10. In Ubuntu 11.04 almost all 5.1, 6.1 and 7.1 cards are supported. In the case of my mother-in-law that was a 7.1 but the other pic card might had been a 7.1, 6.1 or a 5.1. I know the one inside the motherboard is a standard 2.1.
Here is the Alsa support page: http://www.alsa-project.org/main/index.php/Matrix:Main
which will tell you what cards are supported. In many cases it will not say like "Supports Intel DP35DP sound card". Instead it will say the model of the sound card which is general for many Intel motherboards (Like Realtek).
Another post mentioning the problems with the last Creative Labs sound cards is here: How do I get a SB X-Fi Xtreme Audio CA0110 working?
This was almost a year ago. So you can imagine the changes with ALSA after that long time. If not here they are: http://www.alsa-project.org/main/index.php/Changes_v1.0.23_v1.0.24
Basically if 11.04 does not support the card you want to use (Must be the very latest like yesterday) then 11.10 will.
Reference to UbuntuStudio - http://ubuntustudio.org/