TPA3116d2 mono subwoofer board: speaker level inputs?

[gec]

I've ordered on of these little $10 TPA3116d2 subwoofer amps:
TPA3116D2 Subwoofer Digital Power Amplifier 100W AMP Board Audio Module | eBay

I'd like to feed it the signal from a Bluetooth TPA3116 or TDA7492p stereo amplifier board that just has speaker level outputs. Basically upgrade a stereo setup to 2.1, but have the ability to disconnect it.

I wondered if there was a simple floating ground to common ground adapter I could make up and connect to the speaker outputs, or if it would be possible to pick the signal off of the stereo amp between the NE5532 and the class D chip. I'm kind of leaning towards stealing it off the speaker outputs since that solution wouldn't tie me to a specific stereo amp board. It also would allow me to do the doctormord mod of bypassing the NE5532. The old Archer 270-053 came to mind but I don't know what was in that little box and they are hard to come by now.

Any ideas would be greatly appreciated!

 

[wwenze]

a simple floating ground to common ground adapter

Just use a circuit with differential input to single-ended output

 

[gec]

Something like this?
Differential-balanced Stereo Headphone Amplifier Board TPA6132 Hifi Amp for BT | eBay

or this?
150mW Headphone Amplifier Board Differential Balanced SGM 4812 HIFI Amp Module

Is one more suitable than the other? I'm assuming I would need to put something in series between the speaker outputs and the inputs on this?

 

[wwenze]

Yupz those should work. TPA6132 looks like a much better chip than SGM4812.

I was thinking of DIY op-amp circuits but since these are available... with the added functionality of being headphone amps.

You'll still need something between the speaker out and this's input to reduce the incoming voltage, but it's called a volume knob.

Note that volume control wiring for balanced connection is different from single-ended. On the net there are slightly different drawings that achieve the same effect - basically the smaller the value (effective value?) of that middle resistance, the smaller the volume is. Then just wire the pot accordingly.

Diodes for input overvoltage protection may be good to have too. You can even use LED to give it the pro-audio-interface feel.