Why is my Vizio soundbar so quieeeeeet...

So I have an overhead projector checked out from the campus library and it is connected to our dvd player via an HDMI cable. We had some pc speakers connected to the "out" 3.5mm jack, but my wife complained they weren't loud enough.

So I broke out the Vizio soundbar that I had bought on some Amazon special for $50, and plugged it into the 3.5mm jack, and surprise, it is only marginally louder than the pc speakers. I've played with the volume on the remote for the sound bar, but it isn't getting louder.

I'm guessing that the dvd player/projector don't have enough amperage or whatever to push any more volume, and that when we hook it up to a tv it will work.

That is all.

Try a better cable like digital optical if you can.

Our four year old DVD player only has HDMI-out, so I'll just wait until we get a TeeVee, which may be tomorrow.

Is it possible you've connected a line level (line in/out, aux, etc) to a headphone jack? They run at different levels, even though the plug is the same.