In addition to answers you receive here, you may want to run a search for your topics as you will find additional discussions in threads such as this one and this one.
Back to your questions, I use fiber optic cable as you described but my run is 45 feet from my router to my main system. I use LPS at both ends in place of the small wall warts that come with the converters. After conversion, a short CAT 8 Ethernet cable run from the fiber converter to:
- Bonn Silent Angel N8 switch (made by the same people who make the English Electric Network Switch 8), then short Ethernet cable to
- GigaFOILv4-INLINE Ethernet Filter (with LPS), then Network Acoustics Streaming Cable to
- Network Acoustics ENO filter, then the captive streaming cable to
- music server
The set-up works fine and sounds great but I would caution that to me, no one of these things made what I would consider a significant difference in sound quality, especially to the transitional levels sometimes posted about in these forums. Whether that is my components, my overall system and room, or my hearing, I hear nothing more than subtle differences with these tweaks/digital cables.