Digital to Digital decoder?

Does anyone know of a device that will take in a Dolby Digital 5.1 signal and decode it, outputting as 3 digital (spdif/toslink) stereo signals, i.e. pair #1 is left front, right front, pair #2 is center, subwoofer, pair #3 is left rear, right rear.

I know the Tact TCS can do that, but I'm looking for less expensive, less feature rich alternatives.
Rare. I have a player that will do it but most such are expensive or custom mods.

What are you going to do with those 3 S/PDIF feeds and how will you control volume?

I've got 3 digital amps from Tact that take a spdif signal as input. They have their own volume controls. Right now I'm going from a mac mini to usb adapters to spdif to the amps and that works fine, but it restricts my choice of software to those that can decode 5.1 and route the resulting signals to the 3 audio adapters. I'm also not certain how the signal quality is being impacted at each step from 5.1, to decoded, to usb, to spdif. Would like to pipe out the unmolested 5.1 source signal to a box that I know is doing the right thing.
OK. What is your source connection? Is it S/PDIF with lossy multichannel (like DD) or is it something else?

Source is SPDIF Dolby Digital 5.1, so need the decoding but would like to keep signal in the digital domain from decoder to 3 stereo SPDIF pairs.
That is a tough one. For a USB output, my modded Oppo would probably do it. For S/PDIF, I am at a loss for anything other than an expensive processor like the Tact, Meridian or Theta.

Anything else is a custom job.

Hmm, USB output would work if the driver supports 5.1 passthrough in OSX. Can you tell me more about the Oppo?
Sorry. It will only handle FAT/FAT32 USB drives, not the output from a computer.

I seem to recall from a conversation with one of the engineers at Audio Precision that Dolby is really idiosyncratic on some of the types of digital encoding/decoding and input/output capabilities that they will allow manufacturers to have on their equipment and still be in compliance with Dolby's licensing requirements. This was the reason that Dolby Digital testing is handled differently on AP's newer APx units, versus the earlier implementation on the 2700 series.

Dolby's own commercial cinema units of course have this as an option, but that's definitely not a budget solution. As Kal points out, you might have to go to a modified unit . . . I think that MSB Technology may be able to provide this as a service. Also keep in mind that you'll need to keep the volume synchronized between the Tact units for accurate level calibration -- you might make sure that they will do this on their own even without Tact's companion surround processor.
Ok, thanks Kal and Kirkus!