One 15" sub vs two 10" subs

Currently running one Klipsch Synergy 15" sub. Considering going to two 10" subs in order to try and get tighter cleaner lows.
I am using a Yamaha RX A2050 to drive subs, PSB Image towers and center channel.
I have never tried this. I’m looking for others who have and would like to here your thoughts on the experience.
Also suggestions on what subs in the $300 to $500 a piece used range to try it with.

What is the model of Klipsch 15" sub do you have?

If it is what I think it is(KSW-15), you could do much better for music with a pair of quality sealed 10" subs.  Now the KSW-15 is no where near the highly regarded RSW-15.

Look at a pair of new SVS SB1000s which would come in at under your $1000.00 budget.  Or a pair of used SB2000s.

REL is a superb musical sub.  In your example, (2) 10" subs are going to beat (no pun) any 15" woofer.

Another thought- (4) 8" subs are going to be tighter than (2) 10" subs.
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I think it's fair to say that using 2 or more subs is generally better than using one...Especially in a Theater setting. In my set up I use 2 JL 10 subs.  Theater has some dramatic, explosive LFE information.  I find using one sub is not as even and you can localize the sub that is your brain knows where the impact is coming from...BUT with both subs engaged there is no localization and it's like a wave of smooth bass.

The bigger speaker will probably dip a little lower in freq response...

I use an Rel R-305 in my 2 channel that just ever so slightly underpins the front speakers - it is really barely on and only engages at about 28 htz...However, I have tried that sub in a theater setting and it can not produce the wallop without distorting..Just an FYI.