Help needed connecting a Technics and Yamaha AV receiver setup for 7 speakers

[Agent_Smith]

Hey everyone,

I’ve got a setup of 5 Technics speakers running through a Technics SA-EH780 system, which includes a stereo tuner/amplifier, sound processor, CD player, and cassette player. Alongside that, I’ve got 2 JBL GTO speakers (originally car speakers) that I custom-cased and connected to a Yamaha AV receiver. I want to run all 7 speakers together, with the audio coming from my PC.

Here’s where I’m stuck:

1. Connecting the systems: I assume I’ll need to connect the Technics stereo amplifier to the Yamaha receiver, and then have the Yamaha connected to my PC. Does that make sense? Would I need an RCA switch to handle the inputs/outputs since I think that there is no more left?
2. EQ Control: Will my Technics stereo sound processor (basically an EQ) apply EQ to all the speakers if I’m using the Yamaha receiver as the main control unit?
3. Should I use the Yamaha as the main control unit?
4. Sync and Quality Concerns: Should I expect any sync issues or inconsistencies in volume or sound quality by combining these two systems? I’d rather not lose any audio quality, so I’m avoiding low-quality RCA switches—any recommendations for something reliable?
5. Sound Card: I’m also wondering if it’s worth investing in a dedicated sound card to get the best out of this 7-speaker setup, maybe it can add quality? Or is my current MSI X470 GAMING PLUS MAX motherboard will be enough.

Any advice or recommendations would be awesome. Thanks!

Note: Dont worry about the tweeters on the JBLs I will solder them back on.
If you need any more pictures then sure because i couldnt fit in the JBL speakers (10 pictures max and i have 15)

 

[Agent_Smith]

Additional pics

 

[isolar8001]

Wow....haven't seen something like this since I visited an Appalachian trailer park in 1977.

 

[adk highlander]

No. Just no.

 

[Agent_Smith]

No. Just no.

Why lol

 

[Eppie]

My first instinct is to just say NO, but that would not be very helpful. You are going to have to stick with a 5 speaker setup. That is because the Yamaha and Technics both appear to be 5 channel receivers. There are no additional channels to feed to another pair of speakers. Both units do not have any pre-amp outputs, so you can not send a signal to second amp or receiver any way.

If you want to connect the PC, there are five 1/8" jacks for audio out. Most motherboards can auto-sense what is connected. If you connect headphones, it will be stereo. If you connect all 5 to a surround receiver, it will process all 5 channels but that is provided that the source material is 5 channel audio and not just stereo. The 1/8" audio out jacks on the PC connect to the Multi-CH input on the Yamaha or the DVD input on the Technics. You can use individual cables, but I have seen bundled multi-cables that have 5 1/8" plugs on one end and 5 RCA plugs on the other end. You'll need to choose one receiver or the other.