Need advice on adding subs


I’m looking for advice on adding subs to my system.

I listen primarily to small combo jazz and classical but I’m disappointed by the classical symphonic reproduction. I can only enjoy symphonic music on my headphones. Perhaps, I could improve symphonic on my main system by adding subs.

I don’t listen at high volume nor am I a bass fanatic. I just want the better sound. This is strictly 2 channel system. I have no interest in HT. I live in an apartment.

My system:

Balanced Power Technology BP-1 Conditioner
Toshiba lap top with JRiver feeding via crossover Ethernet to
Sonore Rendu
Wyred4Sound Dac-2
Warpspeed Optical Attenuator
First Watt J2 Output power 8 ohms30 watts 4 ohms15 watts

Reference DeCapo MM 2-way Monitors

The speakers are a simple 1st order high pass passive 3kHz x-over to the tweeter. I believe the woofer is designed to rolloff naturally at both ends of its band width.

I’m open to any ideas. Lets say up to $2000 budget.


cjk5933
If you are going used, a pair of Vandy 2WQs would be a bit under your budget.  They are fast, tight and would match well with your speakers since they have a first order crossover as well.  When I had a pair, I set them up just like marktomars.  Dial them back so that you really can't tell that they are on, except when you turn them off.  
There is a good thread currently running elsewhere on the site, under the simple title "Subwoofers" (I think). Duke of AudioKinesis and BDP24, among others, have made some valuable contributions, and it is worth reading. Here’s the link: https://forum.audiogon.com/discussions/subwoofer?highlight=subwoofers

It's a long thread, but worth the time to read through- some thoughtful stuff that I benefitted from. 
I'm not in love with the combo of deCapo and subwoofers.  

The deCapo is beautifully balanced as a stand-alone.  The presence thru treble is gently rolled off to balance the modest bass energy.  As a stand-alone monitor, it's really, really good and IMO one of the best values out there (which is why I bought mine).  When I added a subwoofer (for pretty much the same reasons stated in the OP), I loved the extra weight on the bottom end, but the sound as a whole went dull.  I tweaked it for a long time, but eventually moved on.

I think I'm one of the bigger subwoofer fans on this board and I'm surely one of the bigger deCapo fans, but the combo didn't work for me.  YMMV.
There is no "absolute set it and forget it" answer to subwoofer sound as there is a huge disparity of bass level in music.  I don't like digital room correction devices as they appear to be somebody else's ideas coming into my hifi zone (and my experience as a professional live sound mixer makes my tone ego enormous), so I simply turn the subs (2 RELs) up or down a little here and there…this is easy and works well for me and the room furnishings provide all the "treatment" necessary in my particular listening space.