Card: HDA Intel Chip: SigmaTel STAC9271D View: [Playback] Capture All ...
Codec: SigmaTel STAC9271D
(that grep is slow because the kernel takes a long time to generate the file, probably querying hardware settings, not because it's so big that grep has to chew it for a while.)
But an older AC97 on-board codec I had (some RealTek chip I think) was also only able to use 48k and up. So I guess it's not only add-in cards that resample 44.1->48.
I wonder if dmix can resample to 96kHz/24bit? That would probably avoid any audible distortion, at the expense of a lot more CPU.