Which integrated amp for rock/metal (and why McIntosh?)

Not too many integrated will give you the power you need into 8 ohm. 

Thought bout a separate amp?
***YES, go to a nice A/AB amp. ***


Cool speakers!

McIntosh would be great!
Sunfire is an amazing powerhouse.

Make sure to christen the new speakers with Darkness descends, pleasure to kill, or consuming impulse. ,,/

These are nice amps @mofojo ! And slightly more portable than the 40kg of the PA 3100 HV. Looks nice indeed. I admit I love the sober bulkiness of the T+A. Nothing fancy - just music. 

I thought about separated amps @arcticdeth.  I even considered monoblocks. But in the end, the T+A factory is 2 hours drive away. Stepping up to spending big money (speakers, MP and amp are each more expensive than my wife's car), I really wanted to pay attention to guarantee and repairs. REL sub is new, T+A covers guarantee for 3 years after repairs, etc. 
Honestly, to christen the speakers I was looking for music that would be subtle, vocal, and heavy as well. I eventually settled for Light Field Reverie. https://www.youtube.com/watch?v=J72wtM8d1DM Give it a shot - amazing to feel how the music builds up tension and how accurate the speakers throw it in my living room.

UnderwoodHiFi has a few Wyred4Sound integrates that should be great for you
https://www.underwoodhifi.com/specials

@koenvingerhoets   ---   Thanks for your detailed response to my question and congrats on a very nice, well thought out system. I think the T + A is a great choice.

I believe your T + A integrated is up there on a tier with the Boulder 866, Gryphon Diablo 300, and a few other "holy grail" integrateds that would cost a fortune to beat. I have a good friend who has one and absolutely loves it. For what it's worth, I was a separates guy for years and years, but since I bought the Boulder 866 last summer, I haven't given separates another thought. Now I am curious just how great it might sound driving the Fyne F703 or F704. Do you really need a sub with those massive F704s? I'm guessing your bass must be bone-shaking.

Do you find any weaknesses at all with your new speakers? What has been your experience with breaking them in?

Thanks for your patience in answering these questions. As you can tell, I'm very curious about these speakers. :)

You're welcome @waltersalas 
I had the REL before the Fyne's. I doubt I would buy the REL if I had the Fyne's first. They manage really well, it's surprising but as you now, they have a 360° / downfiring approach; Works well.
No weakness experienced, looks good and sounds even better.
I can record a song on iPhone for you, but it won't be the same as the real stuff.