Wow...I guess these days is quite hard to get a simple answer for a simple question...
First of all you are mistaken, the AES/EBU standard is not "necesarily" limited downwards to 32 kHz:
Digital Audio
Maximum Word Width: 24 bits.
Digital Input Format: S/PDIF coaxial, 0.5V to 5V peak-to-peak.
Digital Input Sample Rate: 8kHz to 96kHz.
Digital Output Format: S/PDIF coaxial, 0.5V peak-to-peak;
AES/EBU data stream over S/PDIF coaxial.
Digital Output Sample Rate: 8kHz to 96kHz.
Connectors: Gold-plated RCA, female, on break-out cable.
The above text is taken from M-Audio Audiophile 2496 manual, a card which I own and can confirm is working properly...except for the latest driver which "limits" the AES input-output signal to 22.05 kHz.
I've even seen some comercial DACs that can accept and play just fine 8kHz even if the "lock" led doesn't come on...you must understand that the "lock" indicator only comes on if the device can properly interpret the embedded flags in the incoming audio data stream and it's not necesarily "a must" for the audio to be played corectly...and is more of a software bug than anything else !
Secondly:
"Nor is a sampling rate lower than what the Nyquist sampling theorem suggests."
What is the Nyquist-Shannon sampling theorem ?
A digitized analogue signal can be completely reconstructed from its samples if the sampling rate is or excedes 2N samples per second, where N is the Nyquist frequency or the highest frequency of the original analogue signal that was digitized...In short the Nyquist freq is always half the sampling rate in a properly recorded signal...11025 Hz for a 22.05 kHz sample rate, 16kHz for a 32 kHz signal etc...
Thirdly:
Probably you didn't understood my words...What I meant is I hate to upsample a lower rate to a higher sampling rate that is "comonly" supported by normal DACs such as 44.1 kHz as upsampling introduces errors in the signal no matter how good the upsampler is, so...it's DEFINITELY better to use a DAC that can sync on the incoming signal no matter how low the sampling rate is...
Fourthly:
I submit you don't own one of these players from Cambridge.
Please reply if you can confirm (by testing) if DAC Magic, 740c or 840c can or cannot accept and play back correctly a digital stream of 22.05 kHz.
Thank you !