What would you do?

My current system: Aerial 7Ts, Parasound A21 amp, Parasound P5 preamp, Wireworld Silver Eclipse interconnect from preamp to amp, Wireworld Gold Starlight 7 digital cable from NAD 565bee CD player to preamp, Wireworld Silver Electra Power cords, and PS Dectet power conditioner. Room treatment with GIK, room is 20'x 24'.

My options are to get new speaker cables, to add a JL Audio F112 or is a new source the answer?
What is the problem?
I wouldn't say there is a problem. I'm just curious to hear opinions on what improvements can be gained by adding a sub or changing my source.
If you tell me whether you would prefer improved resolution, or more bass extension, I will tell you the correct answer.
Maybe look in to some bass trapping in those corners. The room looks great for a system but is a bit sparse IMHO.

My system pictures haven't been updated. I actually have bass traps in the corners.
Improved resolution is more important to me.
A new source makes more sense than getting cables.
If improved resolution is your primary objective, perhaps a more resolving preamp should be in your future. My experience has led me to believe that the quality of the preamp is nearly equal to the speakers in term of importance to the system's character. Better cables seems money poorly allocated, the Wireworlds you have should be more than adequate.
So what I was getting at was that going for deeper, reinforced bass by adding a subwoofer is a completely different matter than improving the performance across the audible frequency spectrum.

I doubt the DAC in either the NAD CD player, or the Parasound P5 are all that special these days. They are reasonably priced components that are decent, but could probably be bested fairly easily by stepping up to the next level. The P5 offers a lot of features for the price, but may be spreading itself a little thin for the price.

If it really matters what I would do, it would be to stop spending more than necessary on cables, and invest instead in individual DAC and pre-amp components that would each cost a bit more than the P5 alone. Or get a better DAC/pre combo unit (which is what I am presently using). I personally am not interested in subwoofers for the 2-channel system any more, having moved the subs to a different system. I'm happy with the bass performance of my current speakers though.

Have fun whatever YOU do.
I ordered a PS Audio PerfectWave DAC II.


Regarding cables and everything that I purchase, I set a price range that I makes me feel comfortable. Believe it or not, with the exception of my speaker cables, every cable that I have falls within the $300 price range. Even my speaker cable was purchased way below list price.
That's cool with the cables. If I had extra money I would buy some fancy cables just for the looks, as mine are very plain looking (Blue Jeans)

The PerfectWave DAC should be great.
Most definitely in your case I would get a new source.

But to make recommendations I need to know your budget.

The ultimate DAC in terms of resolution I have heard is the new PS Audio Direct Stream which guys out my way are going ga ga over. Be wary however its quite sensitive to source quality if you system is very revealing. At a lower price point I would look at a Wired For Sound.

Also its important to be sure resolution is what you really want. To find out I would suggest a comparison between the Direct Stream and Lampazator of the Dac's you are likely to be able to get a hold of. I haven't heard a Lampizator personally, but by reputation it very similar to my DAC, a Killer, which is very musical. You need to hear the difference to know what suits you best.