DAC recommendation

+1 for Mr_m.
The Codex is a great buy for the money.
A close second is the Schiit Gungnir or Yggy. The latter is a bit more (closer to $2K used).
The nice thing is that both Ayre and Schiit offer upgrades as they become available.
B

Just received my Schiit Gumby two weeks ago to use in my headphone system and am very pleased, it replaced a long in tooth Theata dac and am glad I pulled the trigger on it. When things get settled in I plan to drag it down to the big rig and give it a work out.

I don't think you need a new DAC. The difference you are hearing is Spotify streams MP3's and you're playing redbook CD's on your Rotel. A better comparison would be use the digital output of the Rotel to the Parasound's DAC and see how that sounds compared to the Rotel. If you want CD quality streaming check out Tidal.

You don't see many of them come up for sale, but if you could snag a Mytek Brooklyn DAC (the original model), that might be something to consider.
It does MQA, is basically a "pre amp", has inputs for a turntable, excellent headphone amp and a very good ESS DAC chipset.

I have two recommendations, both of which I'd think would bring noticeable improvements over the DAC in your P5.  They would be the Metrum Hex DAC and the Bel Canto DAC3 VB.  Both of these DACs have been favorably compared to much more expensive competitors.

I had the Bel Canto in my system on extended demo (the separate power supply makes a huge improvement as I also had the non-VB version for direct comparison) and it sounded incredibly good to the point where I could not identify any weakness in its presentation and there was absolutely nothing I would've changed in what I was hearing.  It just sounded natural and right.  I'm sure you'd be impressed with its performance, but the only thing I don't know is how it compares to the NOS DACs out now.  Which brings me to the Hex DAC.

Although I've not heard it, the stellar reviews of the NOS Hex attest to this DAC's performance level and capabilities.  My semi-educated guess is that the Bel Canto would present a lighter and more crystal clear view into the recording while the Hex would probably deliver a tonally meatier and weightier presentation with perhaps just a bit less air and sparkle up top.  Red wine versus white wine as it were.  Pick one depending on your own personal tastes and I'd think you'd be a very, very happy camper.  The Bel Canto is available here, and the Hex is on Ebay from an authorized dealer.  Hope this helps, and best of luck in your search.