Has anyone added a small subwoofer to 2 channel and been thrilled with the result?


The subwoofer can of worms.
I’d like to add some bass to my otherwise fine 2 speaker setup and have limited space so perhaps a single 10in?
After a few weeks of research the only conclusion I can come up with is - everyone agrees they have to be setup properly. Every brand and technology has their own following and most recommend using 2 (which I don’t want due to space concerns). My room is 12 x 13 ft with box raised ceiling.
After much research, these are the subwoofers I’m trying to pick from, for various reasons:
Rythmik FM8  - lots of hifi fans
JL audio e110 - fantastic support
REL T/9i - sort of a gold standard
KEF R400b - interesting technology, makes me grin. 

I've never heard any of these.
System:
Hegel H160
SF Concerto speakers on stands.
Ben
casteeb

>I’d like to add some bass to my otherwise fine 2 speaker setup
>System:>Hegel H160
>SF Concerto speakers on stands.
Ben
With little space and you want very good performance, look at the James subs.  
The answer your question yes I think adding a sub really helps. 

I the JL audio E110 is a good choice. If you have a pre-pro or dac to amp you just sit the sub between the two and use the active internal crossover (not just a low pass but a true 24 dB cross-over). Works well and makes blending super easy. 

The only issue I see is two subs are way better than one. I find one sub harder to get a good blend but it can be done. 

I have two E112s and I would say it has been my best audio perchase. Don’t be scared to try a 60hz crossover point. Many will tell you it is too high but with a cross over it is not an issue. 
I have a 10" REL that I've used with several speakers over the years and it has worked well with both stand mount and floorstanders.  I have had the best results with low crossover points, like 60Hz or lower and  running the main speakers full range.   

My dad has Concertos with a Velodyne DD10 and it's awesome for a compact system.  

Some of the newer subs have built in EQ, I would suggest looking at those first.   I'm using a Velodyne SMS 1 to EQ my REL and that coupled with a Auralex isolation platform and it delivers awesome low end .  

JL and REL are great sounding subs in my experience