USB External speakers work by having a Digital To Audio Converter 
(DAC) between the USB and the speaker.  The speaker either gets power 
from the USB port or from an external power supply connected directly 
to the speaker.  The program (or service) that sends signals to the 
USB port is what generates the sound for the speaker.   Most speakers 
do not use the sound card in the computer but generally send data 
bits to the port.   If your headphones work, most likely the sound 
card is OK.  Your speaker has the Cinema System for sound, and the 
computer has the Realtek AC97 sound card which drives the headphones.

That said,  the usual problem with broken sound and garbled sound is 
that the processor is too overloaded to keep feeding the data to the 
USB port fast enough to have continuous sound.   Or something is 
intercepting the sound data and delaying it getting to the USB port 
fast enough.   Check the processes that are taking up a lot of 
processor using the Task Manager and clicking on the CPU heading 
twice to bring the big CPU users to the top.  If something unfamiliar 
is taking up a lot of processor time, that may be a new process that 
is slowing down the sound.

The other problem may be that your USB power source may not be 
putting out the required 0.5 amp at 5 volts (Magic Jack degrading the 
USB 5 volt power?).  That would also cause garbled sound on the 
speaker.  If the speaker has options for an external power source, 
you should try powering it that way.

Hope this gives you some other things to try.

Doug

>----- Original Message -----
>From: Dave@MonroeCommunity
>To: [log in to unmask]
>Sent: Wednesday, April 27, 2011 3:02 PM
>Subject: Re: Sound Problem
>
>
>If your Start up sound play properly on your start up then there is 
>something loading that is changing that. It sounds like you still 
>have some Magic Jack settings Loading. Do you know how to use 
>msconfig to look for something that is starting up that relates to 
>Magic Jack or look for something that refers to some kind of tiger 
>drive. Magic Jack also creates a couple of drive letters in XP that 
>look like CD Drives and a Removable Drive both being USB Drives. I 
>dont have XP anymore and Magic Jack works different in Win7 so this 
>is the best I can remember.
>----------------------------------------------------------------------------------------------------------------------
>PROBLEM DETAILS       [log in to unmask] wrote:
>WinXP SP2 (with a few carefully chosen hot fixes)
>Onboard sound
>Power Supply about 450w to 500w
>
>I have had a Rosewill USB Speaker running for about 6 months. It is 
>a wonderful speaker, beautiful sound. Or it was.
>
>Now the speaker sound is distorted and garbled to the extent that 
>you cannot make out anything from a wmv file. Same with the 
>MagicJack. Although - the headphones still work fine and the USB 
>Speaker plays the Windows start-up music beautifully. To swap 
>between the USB Speaker and the traditional headphone jack, I have 
>to choose either Realtek AC97 Audio (headphone) and ADD-ON USB 
>Cinema System (actually the inexpensive Speader) under "Audio" 
>playback from Sounds & Audio Devices Properties.

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