1991 LS400 radio replacement question

Have a '91 LS and the radio is getting funky (FM doesn't like cold mornings). Would like to replace the head unit. I have a dash kit coming in the mail but I need some information on the amplifiers that are in the car and whether or not I can just use a head unit to connect to the amps or bypass the existing amps and go with a full unit. I tried the search function and didn't get any usable hits. Any help please? Thanks!