There is no mention of a proper phono input in the specification. I can't download the manual, as I don't want to sign up for their BS.
If there is an RIAA phono stage it is usually mentioned in the specification.
So I suspect you either don't have one, or it is no good.
What is your cartridge? If it is old it needs replacement, due to hardening of suspension parts.
If you get a preamp you need to plug it into a line input, not a phono input.
I would be
this cartridge, or
this one.
If either of those cartridges fail to satisfy then your phono input is no good and you will need phono preamp. The one you found should do the trick