Does it sound distorted?
Sounds to me like this TT possibly has a phono stage built in, so you have no need for yours.
Try connecting the TT to the amp directly to the CD socket and set it to Line. If you want to use the phono stage, set the TT to Phono.
As always, start with the volume set very low to avoid damaging speakers, incase you have it set up wrong
Hope this helps!