Turntable disappointment, what did I do wrong?

[Rma]

Dear all,

Thanks so much for your help.
I will follow @eladeb’s recommendation to use a rca/optical converter. 
The only thing I could not test hardware wise is the optical output of the preamp. 
So if it sounds bad using an analog to digital converter connected to the RCA output of the preamp, it will reveal that the defect comes from the toslink output.

Between Xmas, weekend, and COVID lockdown I won’t be able to purchase anything before next week. 

I will keep you posted!