I have a Fiio E17 and E09k combo hooked up to my SPDIF digital out from my ASUS computer board just as you are attempting. Let me attempt to explain.
By the way, this is my first post and I am not an expert, so bear with me.
SPDIF is a digital interface that outputs digital (0's and 1's) information. In our case music in digital format. SPDIF comes in 2 typical formats, they are Optical and Coaxial. The Optical version sends the digital data via a fiber optic cable. This is the connector you show on the back of your computer mother board (a small square door). The other type of SPDIF output is coaxial. It looks like a standard RCA video out (yellow), but it actually sends digital information. It uses what appears to be a standard RCA video cable, but actually this cable is unique for sending digital information only and is a special cable.
Now, the E17 uses the optical digital input and takes a special adapter that should have come with your E17. It has a metal tip on one end covered with a plastic cover to protect the fiber optic lens. The other end of the adapter has a square opening in it that is the same on on your computer. Attached are pictures of the adapter both lay on and plugged into my E17 + E09K. You must purchase a SPDIF fiber optic cable (Newegg, Amazon, etc.) that has a square end on both sides. DO NOT BEND THIS CABLE OR TOUCH THE TIPS ON EITHER END. This is a fiber optic light tube. It can be broken or smudged. Keep it clean and keep covers on the tips whenever it is not plugged in.
First dock the E17 + E09K combo with the power OFF. Then connect one end of the fiber optic cable to your computer motherboard. Next connect the other end to the square side of the adapter that came with the E17. Now carefully remove the clear protective cap that is tethered to the adapter. Insert the plug end (looks like a mini headphone jack) into the SPDIF input on the E17 (that you showed in your photo).
Now turn on the E09K just until the power comes on (volume all the way down) My unit defaults to USB automatically. Since you are now using SPDIF Optical you must press the "INPUT" button on the E17 twice to toggle to "OPT". My E17 unit displays the message "LOCK" when it picks up the optical digital signal. Now increase the volume with the "+" and "-" first (gross volume) and then fine tune with the dial.
One important note. Your computer should automatically pick up the new input device (E09k) as using SPDIF and ask if you want to use it as your primary sound our output device. You need to select yes. If it doesn't automatically ask you to change, you need to go to the Control panel, hardware, sound, etc. and choose all sound to output to SPDIF.
Hope this helps.
NOTE: Tried to attach photos but says I don't have authorization to do so.