I am perfectly happy with Head unit amplifier for normal use. I will get a head unit with preamp out for later addition of amplifier.
What I want to know is if I can use non powered sub directly driven from head unit. Some of the sony head units do have seprate sub out
CDX 5700
http://www.sonyindia.co.in/static/Caraudio/index.html
SOUND CONTROL AMPLIFIER
• S-MOSFET Output Power: 52W x 4
• Pre Out x 2
• Sub Out
• Aux-In Lite
• DSO2 (Dynamic Soundstage
Organizer 2)
• EQ7 (7-Band Equalizer/7 Modes)
• Bass/Treble
• Loudness
• High Pass Filter
• Low Pass Filter
• BBE