Logitech Z506 5.1 Speakers

Dear Forum Members:

I will try not to make this too difficult. I have posted help requests at other sites but no one seems to have an answer. I will try to be succinct, if that is possible given the problem.

2003 – Bought Dell computer & had Altec Lansing 4.1 speakers
2011 – Bought HP computer & continued to use same speakers with no problem

HP Computer – I believe it has two sound cards.
AMD Sound Card – Since I have an AMD processor, they used an AMD sound card for the computer’s onboard sound. I believe that is built into the motherboard and provides only minimal system sounds. No access via 3.5mm connectors in the back.
Realtek Sound Card – I believe this is the discrete unit that has available connectors in the back. (I am wrong about this. I most likely do not have a discrete sound card. The jacks in the back are bunched together in two rows of three each. This means the sound card is attached to the motherboard and is most likely the AMD sound card referred to above. That is the one to which the speaker wires are plugged into. I assume the Realtek software is just that ... software that can be used to configure speakers. I do not believe there is a Realtek sound card on my PC.)

2017 – Altec Lansing speakers finally died. I bought new Logitech Z506, 5.1 speakers. The system has excellent sound.

The Problem

The Given
First, I believe the speakers are correctly connected. The 5.1 sound test via Realtek HD Audio Manager gives me sound from all six sources.

The speaker wires are as follows
One green wire whose ends plug into the Sub and the back of my CPU (sound card).
One conjoined wire that contains one black wire and one orange wire that split at the end, each with its own 3.5mm connector. The back of the Sub labels these inputs as “6 Channel.” I plug the black and orange at the other end into the back of my CPU (sound card).
On my old speaker system, it had the green wire, of course.
However, instead of a combination black and orange wire, it had the green wire and the black wire coming out of the same hole, although they were not conjoined. But there was no orange wire at all.

The connection & the essence of the problem
If I connect only the green wire, I get volume from all six sources but lose all of my Quicken system sounds (beeps, alerts, pings, cash register sound when recording transactions, etc.).
If I then also connect the black & orange wires, I get all of my Quicken sounds back but lose sound in 4 of the 6 sources. In other words, I get sound only from the LF & RF speakers but lose it in the LR, RR, Center, & Sub.
All of my Windows system sounds are fine.

Troubleshooting Attempts
1) I have configured the system for 5.1 speakers via the Realtek HD Audio Manager plus, as mentioned above, I have run a sound check.
2) I have also configured the system for 5.1 speakers using Windows’ generic sound manager.
3) As suggested by another forum member at another site, I have checked my Quicken sounds in the Windows generic sound manager and they test fine.
4) I have checked and unchecked various speakers options in the Realtek HD Audio Manager but none of that works.

My Guess
1) I am guessing that the Realtek Sound Card, assuming that is the one with the available plug-ins in the back of my CPU, is configured for a 4.1 system or below, which is what I had, and that it is not configured for a 5.1 system. I don’t know how to check if my current sound card can handle a 5.1 system other than I’m not getting any sound when I use the “6 Channel” setup. Of course, it might be able to handle a 5.1 system and there is some other problem.
2) I am wondering if I were to go out and buy a “black only” wire to simulate what I had in my old system and plug that into the back of the Sub and into its corresponding opening on the back of my CPU, thus bypassing the black and orange setup of the Sub. It probably would not work but that shows you how little I know about all of this.
3) So I am thinking that the problem is either the sound card or a software setting in the Sound Control Panel.

Conclusion
So that is about it. Any suggestions would be greatly appreciated. I can send pictures of the back of the Sub or my CPU, if necessary. If the sound card is the problem, I have found a Creative Sound Blaster 5.1 for about $35 but I don’t want to have it installed if that is not the problem. Thanks in advance if anyone has any ideas.

Best regards,
Jim