I have always used headphones to monitor sound when playing back clips in camera. I just played back some clips without headphones and the volume through the built in speaker is very low. I adjusted the volume using the thumbwheel, but even at maximum the sound is very weak. Sound is fine through cans, anyone else noticed this ?

I think the size of the speaker this camera has is similar to speakers used in any cell phone, so I don't think you can get any decent volume or quality (which is usually fine).