So I recently bought an 08 IS350 and I've realized something doesn't seem right with the sound system. It feels like the volume should be louder then it should. Even at maximum volume, the it still doesn't sound that loud. I took it to an audio specialist a couple weeks ago. He said the amp was going bad. I got a used oem amp off of Ebay (from a high rater seller). I took out the old amp and connected the new one thinking the new amp would fix the problem. I was wrong. Still sounds the exact same. Does this mean that it might be something else in the sound system or did I potentially do something wrong when connecting the new amp? Doesn't feel like I did anything wrong when I connected the new amp, but you never know. Anyways, if something could help me figure out this problem, that would be greatly appreciated!

 

Have you physically checked each speaker? They could be blown or have a dead spot within the coil. Take an ohm meter and measure out the resistance of each speaker.

 

Try using a different audio source i.e. radio, AUX, 12v bluetooth adapter, etc. This just happened to someone over in the 2IS forum and figured out that their AUX was bad by using a bluetooth adapter.