Since 2021 I am using exactly the same Soundblaster Audigy Fx in a Windows 10 (originally Windwos 7, updated to Windows 10) and later on in a (different) and much moderner/faster Windows 11 system.
I have never experienced any problems, the sound is very clear. No problems with listening to a Youtube channel as well (I like classic music and listen often to Youtube classic music channels).
But the driver I use is not the driver you mentioned (6.0.103.30)!
The driver I used in both systems is SBAF_CD_L13_1_00_07.exe.
Because (on a German site) I once read about problems when you install that driver and that the solution would be to install the driver SBAF_CD_L13_1_00_06.exe first and after that the driver SBAF_CD_L13_1_00_07.exe over that, I did so when I installed the system.
Both drivers can be downloaded from
Soundblaster Audigy Fx at theofficial Creative site.
"Sound Blaster Audigy Fx Software Pack for Windows" 12 Aug 15 Filesize 116.89 MB contains the driver SBAF_CD_L13_1_00_07.exe.
"Creative Sound Blaster Audigy Fx Software Update Web Release" 20 Dec 13 Filesize: 115.7 MB contains the driver SBAF_CD_L13_1_00_06.exe.
When I bought the card, I had read that the driver only supported Windows systems until 8.1 and sent a mail to Creative asking if those drivers were suitable for Windows 10 as well, the system that i was going to use it on. The answer came quite soon and they wrote: "Please be informed that we do not have any reported issues on Audigy Fx not working on Windows 10 OS. The driver posted in our support site works without any issues on Windows 10 OS. Just ensure that your PC meets the system requirements of the sound card." Followed by specs that my PC easily complied with.
After that PC was replaced by a much faster PC with Windows 11 Pro (see my specs clicking My Computer below this answer) I moved the board to that PC. And did the same with the drivers (first the _06 version, followed by the _07 version). And that was and is succesful until this moment!
Maybe it would have been enough to install the _07 version directly, but I did not ever try that.