Head unit amp or external amp?

[Egan101]

di dn po ba pwde parallel nlang yung tweets sa mids?

Nope, each pair of stereo speakers has different cutoff frequencies so you need to power each separately. The reason you use an active (2-way or 3-way) crossover is to segregate the frequency range across the speakers you are using. If you are only using a 4-channel amp plus a mono amp, then just run a 2-way active setup (tweets, mids, sub). A properly-tuned 2-way setup will sound very good.

Hindi, kase unang una baka hindi stable ang amplifier sa final load impedance. 2nd hindi mo matitimpla kase damay ang ka parallel niyang speaker, iba ang frequency response nang tweeter sa mids.

You can still achieve a decent 2-way or 3-way full active setup with the use of an amplifier with a built-in active crossover. DLS used to offer some really good multi-channel amps with built-in active crossovers (Performance CA models, Reference RA models, and the Ultimate models).