How to connect an equalizer to an integrated amp.

The absolute sound review makes that sound like one pretty nice little integrated amp. What you want to go ruin it with EQ for anyway? Ditch that and get on with it.

But oh well. Got to learn somehow. Disconnect the jumpers, connect pre-out to the EQ, connect whatever comes out of the EQ to "main in" and enjoy the sound of whatever interconnects you used added to what used to be a pristine signal. And will be again, when you ditch the EQ.

Not specific to your NAD:

Any equalizer gets inserted in any loop prior to amp, simply add 1 set of cables. Where?

Considerations.

Sub hookup:

a. remove the low bass job away from amp and mains. IOW, don't just add extra bass to small bass shy mains.

Preamp out, to adjustable crossover, to self-powered sub. only low bass to sub, remaining frequencies back to amp to speakers. That takes the demand for low bass out of the amp and out of the main speakers, allows lower powered amps, especially lower powered tube amps (significantly reducing amp price/size/heat/increasing placement options)
eliminates distorted low bass from mains

Equalizer:

After Sub?

Equalize after bass is stripped out, IOW, out of sub, to equalizer, to amp, thus adjusting only frequencies to mains, still able to adjust crossover at sub.

Everything prior to sub? Preamp to equalizer to sub,s crossover, low bass to sub, other frequencies to amp to speakers.

............................

Your NAD, preamp 1, preamp 2, built in crossover, bi-amp, zone 2, OMG

holy crap, read this 21 times, then ask them for help!!!

https://nadelectronics.com/wp-content/uploads/2017/02/M3ENG.pdf

You can connect the EQ to preout2 and main-in, subwoofer to preout1. The EQ will only effective to your main speakers, no effect to the subwoofer. If you want the EQ control subwoofer as well, a pair of ’Y’ connector will be needed.

https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcSs3yzyzYMrWNF0fP65Q4_uRjhNGwPPS2hy3449L3lYAE...