Two subwoofers for two channel music listening

Audio Alchemy says NOT to hook subs up from their speaker binding posts, whereas Paul McGowan (PS Audio) did a video on speaker to sub

Right, but the OP specifically stated his subs have BOTH line level AND high level inputs.  

There is an interesting thing about connections, they are all designed such that if the plug fits, it is safe to use. Check it out. Works for everything.  

Technically, both line level and speaker level are the same. The only difference is the voltage. What do resistors do? Resist voltage. So any speaker level anything can be converted to line level voltage by simply putting a resistor in line. A sub that accepts speaker level, this is exactly what they do. Look at the circuit diagram, the first thing is a 20k or maybe 50k Ohm resistor. Or look at a Line Out Converter, this simple box is nothing more than a resistor with an RCA and terminals making it easy to hook up. Or you can do the same with solder in a few minutes. What I did to my amp, which didn't even have line out. So I modded it. https://systems.audiogon.com/systems/8367 Look at picture #26 to see just how simple this is to do.

To everyone - thanks for chiming in. I just do not want to localize sub bass in either left or right side. If the recording has something coming from left/right, that is fine with me.

@tablejockey - now you know why my user's name is chosen :)))

I have had my stereo subs set up in two ways:  in both methods I have no crossover and the subs serve as bass augmentation.  At first I had my speaker wire running from the amp through the speaker level inputs of two Dayton plate amps (left and right) which have their own binding posts that went to the subs. The speaker cable from the main amp then continued on to the main speakers. So it was kind of like a stop off at the speaker inputs of the plate amps. But without going through any of the crossover in the plate amp. (Blumenstein audio has an illustration of this method). The second method which is what I use now involves the output of my DAC which has both a preamp function and a line level output. I use the standard line level out to my main amp which has a volume control which drives my main speakers. Then I simply run the preamp out from the DAC using RCA to each plate amp which power the subs. The speakers run full range direct from the main amp. The subs are controlled by the preamp output. I suppose this is the same as bi amping but with a low pass filter in the plate amps rather than a crossover. I can control the level of bass using the preamp volume. And because I don’t change volume very often I can pretty much set and forget. Because I can separate left and right with the preamp and the two plate amps I can get true stereo bass augmentation. 

OP:  please see this old thread from about 7 years ago in which I asked a very similar questions. Perhaps there will be some value in it for you:

https://forum.audiogon.com/discussions/setting-up-dual-subwoofers-to-a-two-channel-amp

To everyone - thanks for chiming in. I just do not want to localize sub bass in either left or right side. - confuse_upgraditis

Your name is apt. 

Sub bass cannot be localized. Nothing you can do in the way of hooking them up or locating them on your room will ever change the fact we cannot tell where such low bass frequencies are coming from.