Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Does this use a separate 3mm plug for the sound or does power and music goes over USB?
Document: I purchased this product for a boost in sound quality for my laptop. It is very easy to install (just plug it in) and the performance is what I expected. The key to being satisfied with this speaker is not to expect a loud fulfilling sound for a room. If you want better listening over typical laptop speakers, it's there. For those who expect more, go to a set-up with separate power source.
Great speaker that delivers great sound for laptop computers. It clips to the top of the screen and has a USB plug to power it. Far superior to the internal speakers in the computer.
this works great, I love that it only has one cord - USB (most have 2 cords - USB for power and an 1/8&#34; plug for sound from headphone jack). The sound is a lot better than I expected, I clip it on the top of my laptop and have a lazy day in bed with Netflix
It's cheap and it's small. You need to keep those qualities in mind when considering the Logitech Z205. For travel, it's just about perfect: decent sound (particularly when used with a graphic equalizer such as Winamp provides) and incredibly small and lightweight.That said, it will NOT produce room-filling sound. It gets its power through the single USB cable (supplied) which also carries the audio signal. Plug & Play btw, just clip it onto your laptop screen, plug it in, and go.
It must be plugged in before you start the audio/video player. Then, for the computer speakers to work wnen the Z205 is unplugged, you must restart the player again. (I have not read the directions - perhapa they tell you this. )In summary, if you want the convenience of a little more sound volume than your Laptop, in a very portable speaker that does not require a power plug to use, the Z205 is a good choice.
That was a nice touch.- Weight: The unit was light enough that even though we used it on a netbook it did not cause balance issue - this is a big deal that is often overlooked.- Volume controls.....well, we pretty much just kept it at full volume and modulated it using the built in soft audio controls, so I cannot comment on how well they worked.- USB Connection: The one step USB connection was great; no batteries, no separate power cable.
This is a great speaker. If you're looking for a small portable speaker for your laptop, pad, phone, etc, this is it. Forget the clamp - you'll be lucky if it fits your laptop. I usually sit the speaker next to the laptop. It has plenty of volume, surprisingly good sound, and you never need to worry about the batteries running off since it runs off 5v USB bus power. I often use this with PowerPoint presentations with a room full of people.
This speaker only uses one cord (the usb) for both power and sound, so you don't have to keep track of two separate cords.
I wanted to use it as an external speaker for my iPhone, but without a USB power source, the speakers wouldn't play.
I have a Toshiba Thrive table with the usual tiny poor speakers. This device works great, not room filling, it's no 'boom box', but I think plenty loud enough. My tablet does not use the USB audio source, just supplies the power. It means one more cable (1/8&#34; male stereo audio at each end, not supplied, bought a 3 ft 'er at Radio Shack), no big deal.
Answer: Sound and power are all done within the USB