Two Subwoofers Connection Advice

I have a Dayton Audio plate amp that has the same Y cable suggestion. I never tried it because I ran a single sub for 23 years using two ICs to LR inputs. The amp died and I replaced it 1 1/2 years ago and now it is malfunctioning anew  and have to send it back under warranty. The fun never stops.

I have since moved it to my bedroom and use the single LFE connection from my KEF LSX IIs thanks to excellent advice from a SVS tech who also owns KEF and was helping me set up my new SVS dual subs in my main system.

Long story short: I would heed Velodynes instruction until you contact them.   

I believe every powered sub with stereo inputs has a summing circuit as its first stage prior to amplification. The only benefit of Y connecting is a 3 dB increase in level, which is equally easily achieved using the AVR bass level settings or the sub’s own input level control.  

What @joshua43214 said. 

I had a Marantz receiver and ran two subs.  If I recall correctly, the two sub outputs were a single mono output that was split inside the unit to offer two sub "outputs".  Your best connection will likely be a single RCA cable into the LFE or mono input on each sub.  Good luck and cheers.  

I was still trying to set up dual SVS stereo subs for the first time. A week into the process I was having  no success adjusting both subs at the same time to identical settings. I had reached a high frustration level while keeping my blood pressure under control, but the sound was a confused mess. I'll sleep on it.

The next morn in the shower (please don't try to picture it) it came to me that trying to set up two subs at the same time was a fool's errand. I decided to run L&R ICs to each sub and set it up individually to the mains and room. Before embarkimg on this path I called SVS support for their experience. She was unresponsive to my plan of single sub setup but gave me two useful pieces of advice:

1)Because of the room the settings on the two subs can vary wildly. MY room is VERY different L vs R!

2)When you remove one interconnect when reurning to stereo you will lose 6dB of sound. Good to know!

First I ran both ICs to the R sub which was in a position I had been usimg for a single sub for 20+ years. In less than 10 min I achieved perfect intergration thanks in part to SVS's app, the best app on the planet. I set those perameters to a preset.

Next I ran the ICs to the L sub, forgot the previous settings, and duplicated the process. 10 m later the sound was extremely pleasing. I set the preset and compared notes. Yes, the two settngs varied wildly!

Then I wired the subs in stereo and added 6bB of gain to each sub. I put on some music and was greeted with one of the biggest and most profound improvements my system has ever had. It was  worth the journey for the valuable knowledge and profound beauty dual subs have given me! Go dual as soon as you can!