Dear Sir.

My LS430(2001) is have a pioneer power amp. not ML series.

What about the grade of pioneer power amp in car audio world?

And

I'll buy the clarion HX-D1 and will replace the OEM head-unit.

Is it possible?

please advise to me.

Thank you.

 

Not sure what you mean by grade?

Yes it's possible to replace the head unit. You should consider adding an amp and replacing all the speakers given the age of the car.