Newb, How to tell what OEM Head Unit and where's the Amp?

Hey everyone,

Just bought a '12 Prius Three with Solar Roof and NAV and 6 speakers. I'm working on upgrading the sound system but don't know what's in it to begin with. There is not any amp under the passenger seat. I don't see any JBL logo's anywhere. However, I've turned the Treble, Mid and Bass up and have to say it sounds pretty damn good for factory. Especially when the volume is at 30 or higher. I don't get any distortion which leads me to believe there must be an amp. Somewhere?

Any specific help would be amazing.

 

Thanks ChapmanF

Did a bit more research and realized there's an ID # 57032 on the face of my HU. This is definitely not "JBL". As I initially mentioned the sound maintains it's integrity without distortion at max volume, all the way up to 60.

So it must have a built-in Amp as you mentioned in the HU. I think for now, I will add a Powered Sub-Woofer and see how that improves the quality and range of sound.

Does anyone have any comments on the Bazooka Powered Tubes? I'm looking at the 8" 100W unit (BTA 8100FHC).