upgrade help

[talisker]

i've bought a new alpine headunit which only has one pre out, i've got this amp which i had in my golf a few years ago it's a: hifonics eagle
Amp Specs:

4 x 45w or 2 x 150w @ 4ohms or 4 x 80w @ 2ohms

Noise rating 105dB

Frequency response: 2Hz to 150kHz

Height 50mm, Width 176mm & Length 252mm

Built in crossover features:

Amp source input selectors: High, Low & Full

Switched Mono/stereo low pass

Selectable line outputs

2 Independently variable high pass filters and 1 independently variable low pass filter

am i right in thinking that all i can use this for is to power the front speakers, i would have liked to have had a sub add as well.