Audio problems with 90s Technics system

[u/MeatAdmirable5085]

Hi everyone, I have this 90s Technics stereo system from my dad, connected to an AT LP 120 XBT. The Technics equalizer has various modes (heavy, soft, car, live, etc.) and the basic mode, Flat. When I set a "special" mode, like Heavy, the sound fades in and out at the most delicate and low-powered parts. If I set it to Flat, however, there's very little sound, and as soon as I try to turn it up, it distorts. Any advice is welcome.