One 10 sub vs Two 10 subs

I have one 10" dual-voice sub in a sealed enclosure that sounds nice, but I'd like a tad more bass without going overboard.  Would adding a second one give me a volume boost or would it merely change the tonal qualities?  I'm just wondering what results I'd get before spending the money.

BTW, I have an Alpine SWR-1041D.

Adding another sub will change the load on the amp, if you intend to run them both together off the amp you are currently using to power your single sub.  And will increase the power requirements of the amplifier.  The overall system power will also increase, so take all wiring, fusing and car power sources into consideration as well.  As long as you draw it all up on paper, look at it and see what all you have to change, then you'll be OK.  I think you would most likely like the sound of two 10's, too.

One sub gives you wiring options of either 2 ohm or 8 ohm.  Two subs of this type would give you options of either 1 ohm or 4 ohm.  wiring wizard

If you have 4 ohm coils and have them hooked parallel(2 ohm load) Then if you have to hook another one of the same subs,you will have to hook each in series and then hook them parallel which makes a total of 4 ohms =amp puts out half the power it was putting with one sub = waste of money for the second sub

If you want more ditch the dvc sub and get two svc ,that way you get the amp power .