I just bought a Polk audio psw111 compact powered 8 subwoofer, And I would like to use my existing Creative Pebbles PC speakers as satellites. The Pebble speakers only has the 3.5mm jack to the PC and the subwoofer has rca line in jacks and straight wire line out for speakers. There must be a way to do this but I can't figure it out. If anyone knows I would appreciate the help. The pebble speakers are powered by usb to pc.
if your pebble speakers doesnt have rca outpot for sub, then u can connect sub to your PC (with 2x rca male to 3.5mm male cable) then u plug your pebble speakers to line out on your sub
for that u can either cut your 3.5mm jack to get wires for your sub or u can get female 3.5mm TRS to 2x RCA where u cut RCA to get wires
If your speakers are not the Pebble Plus model, then you don't have the "RCA to subwoofer" cable as shown in the above pic that @kerberos_20 linked to. I do not see a line-out on the sub, so you cannot connect the Pebble speakers to the sub for a signal source.
Here's how to connect it. Connect the male end of the 1/8" TRS splitter cable to your source (PC audio out, usually a green jack on the back of the PC). Then connect the cable that kerberos_20 linked to, one end to the splitter on the PC and the other end to the rca jacks on the sub. Then, connect the Pebble speakers to the other leg of the splitter coming out of the PC.