[linux-audio-user] full duplex USB<->SPDIF converter recommendations

I would like purchase a very simple and straight forward USB<->SPDIF converter and do full duplex streaming (i.e. record sound from SPDIF output device, process the sound in Linux and play it back to SPDIF device in real-time). Would LOVE to know if anyone can recommend any of such devices (esp. from personal experience, for example Edirol/Roland UA-1D or Opcode DatPort appear to be such devices - only do they work on Linux...) USB<->SPDIF converter *must* work in *full duplex* mode (with ALSA generic USB driver or any other if such is available for Linux). If you do have something to recommend, then I would like to stretch your patience and ask you a question regarding the device/model of your choice: considering, that USB<->SPDIF converter is capable of recording SPDIF signal - I presume that it is capable of syncing to incoming input (i.e. otherwise clicks would occur). Also, given that the device is capable of playing to SPDIF device - it is assumable that USB<->SPDIF converter has its own internal clock (i.e. not recording anything, just playing signal back to say a DAT machine which will need to sync to the signal produced by USB<->SPDIF converter, etc.). Would I then be correct in thinking that if such is the case - then there would be some way of controlling whether to use internal clock or to sync to external signal - or would be such decision made automatically whenever deciding to record - USB<->SPDIF converter will lock to incoming signal (in such a case - it is important to know it, because problems could arrise if for instance single DAT machine was used as AD/DA box *and* set to sync to incoming signal - this way DAT machine would try to sync to USB<->SPDIF converter, whilst USB<->SPDIF converter would be trying to sync to DAT machine... pitch shift anyone?) Kind regards, Leon.