hi.. wanna ask bout setup.. noob about ice here..

just buy a 2nd HU kenwood from a member.. is it got amp?

now using it to blast :
2x front speaker (mtx audio)
2x tweeter (jbl)
2x 6x9 speaker (mtx audio)
1x underseat subwoofer (2 speaker inside - kenwood JDM model)..

so.. when installing the new HU, i just know that my car previous owner put an amp underseat and install a cross over for the tweeter (jbl).. but he already take the amp out, crossX still avail.. so now how to setup back? do i need to buy another amp? how much wattage? how many channel?

running without amp now.. just depend on subwoofer amp to blast.. seem like speaker not getting enough power..

i love the tweeter but sometimes, the low pitch sound.. damn hurt my ear.. anyway to reduce it (pre-amp?)..