My fancy tuner/receiver will be reduced to stereo output, going to a graphic equalizer (a gift). I need a THINGAMAJIG that will take stereo outputs and divide the sound back to 5.1 / surround again. The subwoofer shall remain connected to the receiver. WHAT IS THE TYPE OF, & NAME OF THE THINGAMAJIG?
Once 5.1 has been combined to stereo, there is no good way to get it back. Dolby surround simulated the 5.1, but it was just that simulated. If you want 5.1, you need to do any audio processing on the receiver.
There is no thingamagig to do what you want. You can't use a stereo EQ on 5.1 channels. Each speaker type would need it's own EQ.
If you wanted to use it to adjust the main front L/R speakers you would need a preamp output for the EQ (or a speaker to line level converter) and an external power amp to drive the speakers.
You could use it with one analog source to EQ that.