2 subs connected to a 2 channel amp?

@wolf_garcia are you saying that you have 2 subs connected in series across the Right and Left negative speaker terminals? Such that each sub’s negative terminal is connected to the negative speaker terminal and each positive sub terminal is connected to the other, i.e. ‘joined’ by the red wire? 
 

Or, are you ‘joining’ Left and Right Speaker positive terminals to each other before going out to the positive terminals of each sub? (I.e., a parallel connection)

Trying to figure out how you’re getting three wires to do the work of four.

Jeremiah

@larry5729  "If you purchased a pair of REL subwoofers you wouldn’t have had to deal with this."

Is there something special about the REL’s? Wouldn’t any sub with a high level input work? Seems there are a few including HSU, Rythmik, etc

This is a crazy topic as I'll find one discussion seems to say "high level connection is the right way to connect an amp with no sub out" and then the next discussion will say you need high level to line converters, etc.  

I have a Node 3, SMSL DAC, 2 powered speakers and 2 powered subs.  From the DAC I have one coaxial cable to each speaker and sub.  The speakers use the 2 RCA outputs, and the Subs use the 2 XLR outputs.  Works well.  Since the DAC in the Node is bypassed, I assume that the speaker and sub outs on the Node are disabled.  All of the audio controls on the Node are disabled, so I control the volume on the DAC.

Yes...joining the positive REL wires and plugging 'em in the back of my amp. RELs use a 100,000 ohm signal each so the amp has no idea they're connected, and the damping factor of the Pass XA-25 is 500 so that is still in play...more bass control supposedly. Also works fine with my single ended tube amp.