I’m not an audio guy here, but I wonder if the Clip just doesn’t have enough driving force to produce the volume you would like with the speakers , given their audio characteristics. If you wanted more volume, one thing you could do would be to get a small amplifier to use between the Clip and the speakers–while it sounds like a big deal, it really isn’t and there are some nice, inexpensive ones out there (such as by FiiO) that you could try.
I agree. These little mp3 players only put out “milliwatts” of power. They are only designed to drive ear-bud type phones stuck directly in your ear canal, not provide “room-filling” sound.
Adding a headphone amp would help, although a better way of doing it I think (with less hardware too) is to get AC-powered Computer Speakers. Some of them have sub-woofers as well, and are relatively inexpensive.