Hello.

With an firmware not updated since «Last update May 9, 2011»
I think it's safe to say that this card will never work at higher
sample rate - running linux.

It's not «legacy» on the Sound Devices web site, i wonder why.

The list keep an old talk on this card and this problem : 

https://lists.linuxaudio.org/archives/linux-audio-user/2014-September/099206.html

Older : 

https://lists.linuxaudio.org/archives/linux-audio-user/2013-January/089199.html

And i can quote a support email from Sound Devices where i asked about
this issues - wich is not an issue for them for sure.

De : John Doe <JohnDoe@sounddevices.com>
À : "me@yahoo.fr" <me@yahoo.fr>
Envoyé : mercredi 10 décembre 2014 à 16:58:13 UTC+1
Objet : Sound Devices Product Inquiry (33173)

Hello You,

Thank you for contacting Sound Devices.  I don't know when or if they
will make this request available but I will gladly pass this request to
engineering for future firmware consideration.  Thanks.

Best Regards,
John Doe