6 Channel Direct Input (1 Viewer)

OK, this was a really dumb thing to do. I purchased an old Marantz 74SR770/02 (commonly called a SR-770) as I was going to use the front pre-outs to connect to speakers on another amp. I didn't bother to look at what inputs the Marantz has and I now see that for surround sound it only has 6-channel direct input. The outputs on the devices I was going to connect to it (TV box and laptop) are digital. Am I totally stuffed here or is there some device that will convert digital to 6-channel analog?

$60 on Amazon.

Have just ordered a 5.1 SPDIF Decoder for HD AC3 DTS Digital Audio1) Input: 2xOptical,1xCoaxial,1x Analog Stereo Audio2) Output: CEN, SW, FL, FR, SL, SR, 1xUSB3) Transfer the DTS/AC-3 digital signal into 5.1 analog output (FL/FR if 2.1).