The eclaro has a 3.5mm miniplug female connector for the sub and the front speakers (1). Unless there is a creative solution you are aware of or there is such a thing as a cable with one 3.5mm to 2 pairs of banana plugs, I probably need another piece of equipment.
1. Do cables exist that will enable me to connect these items together?
2. If I need to purchase another piece of equipment, what do you recommend?
3. Would a Klipsch ProMedia DD-5.1 Multimedia Digital Decoder Preamplifer help? I think it will solve the cable issue, but not sure if helps/hinders performance. (I happen to have one of these): http://www.klipsch.com/promedia-dd-5-1
So why don't you get either a DAC, or a reciever with an optical in to power the speakers?
Edit for clarification: Having a soundcard isn't going to help you at all. Optical is a digital signal so it really doesn't matter if it's coming off the sound card you bought or directly from the mobo's on-board optical out.
I just bought my first receiver (Denon 2113CI) for a full blown 5.1 system, so I can't really help you too much.
On my PC I'm just using an 8 year old Sony receiver I got for free from a friend and it works fine. My guess is you could just get something cheap on Craig's List and be happy.
One issue I see regarding controlling everything from your computer...you'll probably need to set a max volume on your receiver that corresponds to the max volume on your PC and then only adjust the volume on your PC if that's how you want to control it. I don't mind turning the nob on my receiver so I just have my PC volume maxed out and adjust volume using the receiver.
What are you planning on doing with the system? Just music and PC games? I don't see any point on going the HDMI route if you're not seriously considering going 5.1 in the near future.
Passing audio through the optical port to a receiver is more than sufficient, especially if you're sticking with 2.1 for awhile. Not much point in spending a bunch of extra money on a new video card just to support newer surround formats if you don't need them.
I am not sure about 5.1. I may do it if I can figure out how to fit everything into the room. It is possible I may never do it. If I can get the 2.1 working cheaply, I would probably just do that and worry about extra expense later for explansion. Does the HDMI have any real benefits or limitations I should consider?
I asked the same question on the Polk forum board and one person came up with an excellend solution: Adcom GFA-535 amp. The wiring goes from the sound card to the amp to the sub to the speakers. The beauty of the solution is that it is cheap, delivers quality and enables me to control everything from my PC.
Thank you all for your help. I used the information you provided on the different forums to reach the final solution.