Hi 

I use dual subs in my Sonos with great results….however there are few caveats to consider….

Placement of a single or dual subs is most critical. Trueplay can’t compensate for a sub in a poorly placed position. Best placement is in a corner wherein the sound waves have two walls and the floor to amp the low-end response. Placing the sub behind a sofa or under it can offer improvements in low-end response. A well placed sub is invisible...meaning you should not be able to determine where the sub (or subs) is located. Low-end (bass) should be non-directional. 

Room topography is important as well. Rooms heavily furnished with sound absorbing materials such as plush seating, carpet and drapes can reduce the low-end response. In fact such rooms mute all frequencies (high, mid, low). A hard surface room with tile floors and lots of glass (windows) can also have a negative affect on low-end. 

Dual subs really improve the low-end and are most noticeable when viewing movies with a lot of low-end sound effects. Movies in stereo and/or broadcast TV don’t really push the low-end.

I listen to a lot of smooth jazz wherein lead instruments are mainly brass, piano and guitar. Bass is mainly an accent sound for affect and not overly pronounced. There are a few artists where the lead is  bass guitar wherein the low-end is amped. 

All said there are many factors to consider. Don’t expect a noticeable improvement with all source materials.

Thank you for your reply. I have both subs up front against the wall on each side of the entertainment center.  My problem is the second sub really hasn't been noticeable on those low end sounds.  Do you typically have your sub level up high around the 6-8 mark (not 15, max)?  Is that safe for the subs to have up that high?  I don't want to blow the subs but want to make them impactful as well.  

Hi

My dual subs are adjusted by Trueplay tuning. So whatever level is set is where they remain. However you can adjust the sub volume level to your liking. If the sub “clips” during a passage then the level is too high.  FYI, for more information on what “clipping” is click  here.

My room (in feet) is 20 L x 16 W x 8 H (only one doorway on left wall at rear) which encapsulates the sounds waves to a confined area. TruePlay has a more difficult time adjusting things in an open area where it takes longer for the sounds to bounce back to your device microphones with somewhat less accuracy. I’m not saying your room is at fault...just providing some background information.

If you can distinguish which sub is not responding then there are two possibilities:

1. The sub (or subs) are not positioned properly
2. Th sub with less volume is defective 

I’m leaning toward #1. So, I suggest you experiment with placement of the subs.

Even if an explosion in a move for example is to the left or right the low end will not be directed to that side by the sub. The Sonos sound bar will provide direction by emphasizing the left or right front channel and the surrounds will mimic the direction as well.