All-in-one integrated, 10-15K range, class A/B only

The gryphon Diablo 300 is built world class looks great and beats 
seperates that cost over $20 k .my brother owns one .just check out any current review ,for less then $8k the New Krell 300 is very good sounding and has hdmi,inputs and outputs meaning you can have a direct feed to your  HD TV, both have a nice warmer natural balance.the Gryphon is the best integrated I have heard to date and I have heard the $20k Dartzeel which is excellent the gryphon 
is more powerful and will double down to under 2 ohms to over 900wpc  great head room which you should always have much more then you need. For sure check ot the Krell though 
it stays in pure class A up to over 90 wpc Thatis more then most people listen to at90+ db spl. You didnot mention what kind of speakers you are driving I owned a Audio store for years and system synergy is very important ,when looking to upgrade 
please state your speakers  and efficiency .

If you go the route of using a separate dac/ streamer, try the Naims. Even the entry level model has great sound. 

The Hegel H590 is 300wpc and $11k new. Open box around $8k. Reviews are very good. The H390 seems to be the better deal at 250wpc and the same dac and features. It is $6k, but it can be purchased closer to $5k. I recently upgraded from a NAD C388 to the H390 and I absolutely love the H390!

I own an Aesthetix Mimas with DAC and phono modules. Excellent integrated and under $10k.