Hmmm... JRC(or others)4558 is a pretty old dual opamp, nothing special.
I can recommend as preamp. some TDA IC with voltage controlled volume and tone... but 500W PA no idea.
please if TDA is the best kindly give me the link.
Please if TDA is the best kindly give me the link regardless the output power. I'll fix the final output power my self. please kindly include the tone controls. if it has any. thanks.