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

If there is only one amp that hits all your boxes, then the choice is already made, ie, there is no choice, but only one option. So go ahead and swipe card. Why even bother discussing things.

But all these amp x is the best and most sublime, gods gift to mankind because its the most expensive...that is pure and utter BS. Most of us have no need to believe that because we don't drink that kool aid. This is similar to the review of Avik U380, a 40K class D amp which is god's gift to mankind, except it measured so bad in the bench that it was deemed broken in transport. Or that same designer's Raidho 2.5 way speakers costing $50,000. Getting stellar reviews by Absolute Sound. Yeah. Great stuff guys. I will buy a pair of $70,000 subwoofers to fill out the low end. And also buy $25,000 cables to "tighten" the sound signature.

You should audition Luxman 509 or 590axii.
I was also looking initially for all in one and hence bought Naim Nova. I was running (still run sometimes for a change) my aerial acoustics 7T with Naim Nova. I love them and still have it, probably will keep it. I recently bought Luxman 590axii, as I wanted more musical class A tube like sound. They are end game amplifiers. They have not even broken and am already in love with it. They are different level all together. They are more than sufficient to power any speaker with decent sensitivity. Their rated 30 watts is very conservative. I am using Nova as streamer/DAC to Luxman 590axii. Eventually I might change Nova to reference quality streamer/Dac. I am now researching which streamer/DAC to buy. The idea of all in one is always intriguing but I am settling for streamer/DAC and integrated amp combo. Again, keep Luxman 509 (if you want more dynamic sound) and 590axii (more musical) in your list. 

Trying to decide between the 509x vs the 590axii. What does more dynamic sound means vs more musical? I guess more musical means it's more smooth and flows nicely?

I am no expert, but dynamics is more to do with clear delineation across various dynamic spectrum of sound (soft to all the way up to loud notes). Little bit more analytical and may be more definition of every spectrum. Yes, musical is very smooth, without much emphasis of clear distinction of various notes. Just melowy and emphasis on high and mids. 

Thanks. I suppose why audiophiles swear by class A is because of the smoothness. I read they do not prefer A/B because of the "noise" that they hear (or could it be caused by the "definition" and clarity?). In theory, no recording is perfect and so maybe with the higher definition, they are hearing the noise from the recording and not really the noise from the amp?

I've heard the 509x (A/B) and it sounds nice. Have not had a chance to hear the 590axii (A) yet.