What is the Spinbase not doing for you?
The Spinbase Max just seems to go a bit lower than the original Spinbase so it's not worth switching too especially not for $500 since if you want lower bass then add a powered subwoofer for much lower bass that you can feel.
Do you have a subwoofer size and budget in mind?
No need to change cartridges, you can upgrade just the stylus to OM10 or OM20 or LP Gear OM10 $39 is a good value.
If you are looking for better sound quality and you must have a vertical setup under the turntable then you could get a turntable stand and place a better pair of speakers in the top vinyl storage area.
Klipsch the Fives powered speakers with a built in phono preamp.
Or an amp or receiver and passive speakers:
The top record storage shelf may even allow the tweeters to be at your seated ear level, scroll down to the speaker height section.