I’m looking for an sleek integrated amp under $15k

As a ex audio dealer ,that is not a sound request , for many reasons 

separate allow much better isolation power supplies, digital separate streamer,dacs  

for digital has advanced a lot ,innuos has very good entry level SS HD,streamer 

with excellent interface , you can add the LPS later , the T+A A200 dac-Preamp 

which has excellent galvanic isolation in every area dac as good as Anything  up to $15k+ the preamp is a excellent class A discreet type in the$5-6k class pick a decent power amp, Coda very good with discounts $5k as a example .

my point separates give you future flexibility.

You should be able to get a Gryphon Diablo 300 with DAC option at $15k as the new 333 is out (or coming soon).  It is one of the best integrated amp at this price - lotsa power.  It will blow away the Naim. What speakers do you have?

McIntosh MA12000.

I have a Lyngdorf Processor. Absolutely love it. Sounds incredible with great workmanship. My votes for them. Good Luck and Happy Hunting  

I have never heard an integrated amp over 5K and probably never will. Based on reviews, I'd want to hear a Simaudio model for sure. 

I would never look for one with a phono input but a separate phono preamp.