Raspberry Pi to older computer speakers with subwoofer

[corminos]

I have a set of computer speakers with a subwoofer. This was connected to a sound card with 3 outputs: stereo; surround; and subwoofer/center.

I've tried connecting the raspberry pi single audio out to the subwoofer/center input and it works "okay".

But what I would really like to do is to get the full use out of my speakers.

Do I need a product like this: https://www.amazon.co.uk/dp/B07QXS466Z/ref=sspa_dk_detail_8?pd_rd_i=B07QXS466Z&pd_rd_w=NltIg&pf_rd_p=1055d8b2-c10c-4d7d-b50d-96300553e15d&pd_rd_wg=UYuww&pf_rd_r=A695XYASS2C28KN80XHT&pd_rd_r=75b1d851-e6ca-4af7-91a2-9a69079f2072&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExTkNDUTQ0N0NOSFdKJmVuY3J5cHRlZElkPUEwNDU2MjQ4M0xCOEk0QkRJS1BBOCZlbmNyeXB0ZWRBZElkPUEwNjc3MjE2RUlFNlM4Q1o5VTJDJndpZGdldE5hbWU9c3BfZGV0YWlsJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1 - Docooler External Sound Card Channel 5.1/7.1 USB2.0 Optical Audio Sound Adapter

I'm assuming that I would just power it with the USB and connect the raspberry pi to the 3.5mm input jack. Or is there a better way?

I would prefer to not buy new speakers and an amp.

Thanks in advance.

[sirhenrythe5th]

Concerning the Hardware: as far as i see it you will have to buy an external 5.1/7.1 channel decoder.
The Pi has a simple stereo/2-channel output, there will be no way to cast a spell and have multi-channel-audio.

Concerning the Software: is there any system emulated on the pi that has THX, Dolby5.1, dts or similar?
N64, PSX, Dreamcast...those are the latest systems that are possible, and they all had stereo-output as well.
Do you really need a surround-system connected to the pi?`
I just bought a 2.1 Subwoofer-System used for 20€ (about $25) from Logitech and it does a great Job.
Without expensive extra Decoders :/

[corminos]

@sirhenrythe5th Considering it will cost me about as much to buy the decoder and if it really won't do anything else, I might as well get some different speakers.

Thank you.