Non-fatiguing speakers in $10K range?

GoldenEar Triton Reference based on my experience with the speaker. Great value for money and Class A rated on Stereophile. No listening fatigue for me.
 

+1 @jfrmusic

Surprised that you’re the only one to suggest Harbeths. Every speaker in the line is voiced beautifully. I have little tolerance for high-end anomalies and the Harbeth "ruler-flat" response curve does the trick for me. No matter what electronics I've thrown at them over the years, they’re always smooth as fine cognac.

And despite middling sensitivity, they’re an easy load to drive & relatively tolerant to room placement, and their post-BBC thin-wall design makes them fairly compact & lightweight. Lots of selling points.

@alvinnir2 mentioned that he liked his Harbeth CS7ES3s, but bemoaned their lack of bass (bottoming out in the 40-45Hz range). I think he’s right on the money there, esp. given the OP’s emphasis on rock/metal. But keep in mind that the CS7 is one of Harbeth’s bookshelf models, currently selling in the $4-5K range. My own pair, mated with a good sub & amp, shake the floor & produce painful sound levels in my 14x17 room. The many Harbeth reviews in Stereophile & TAS suggest that most Harbeth models have similar voicing, differing mainly in dynamics & low-end. The larger models, especially those in the OP’s price range, might do the job for the OP in an average-sized room, even without a sub.

Vandersteen Treo. Beautiful build quality and design, very natural without harshness. Haven't heard em, but wonder how PS Audio FR 10's would hold up to your needs. They're on a significant sale right now.

I have the Harbeth C7ES-XD. For Classical, Jazz and Pop they are wonderful. 
I found in my room they have plenty of deep tight bass. I actually sold my two REL T/5X subs. I’ve listen to the 30s and the 5+ and liked the C7s the best. They have the most open airy sound of the bunch but all Harbeths are extremely fatigue free and scale up the better the down stream equipment. Wonderful midrange and smooth highs. Vocals are life like. I love British speakers and have owned Quad, Kef,  B&W and ATC. Harbeth to me are best and most fatigue free. 

Now, music-wise I do not listen to jazz or classical or vocals, sorry. Classic rock, hard rock, 80s new wave, punk, pop (classic and modern) and African blues like Tinariwen. People tend to insta-suggest forward sounding speakers - you like metal, right???. But I don’t like piercing sound and I rarely go to concerts exactly because of this. I listen to AC/DC but NOT at ’realistic’ revels. I like rhythm, melody, but I don’t care about 120 Db.

Considering your tastes in music, you shouldn’t be taking any speaker advice from guys who listen to female vocals/Diana Krall @ 60 db... Metal/Hard Rock are harder genres to obtain a high fidelity listening experience with choice of gear. As a long time fan of hard rock & metal myself, it took me a while to get that sorted out. Guys who know nothing about such genres are the ones who come up with Klipsch, etc. The latter is a lousy speaker for metal, in reality.

If you want your hard rock and metal to be "high fidelity" (and also do justice to your 80s new wave and pop)... a couple of speakers that are above your budget comes to mind.... But, not to fret, you probably won’t be able to beat the GR Research "Bully" for your money. If you are not a DIY guy (it is cheaper if you can DIY the kit), it appears that you can obtain a finished Bully from GR research for 5k to 6k now with the finish of your choice, i.e. 4k under your budget. Good luck with your search...