What would you do?

If you tell me whether you would prefer improved resolution, or more bass extension, I will tell you the correct answer.

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.

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.