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

Thanks @stereo5 and @archguy for your concern. I can pick it up in the original box - so all ok on that side.

After reading reviews and comparing technical sheets for hours, I'm focusing on
- Hegel H590 (has all the connectivity I need)
- Gryphon Diablo 300 (as the amount of positive reviews are just massive)
- McIntosh MA9000 (as it started my hunt for the next amp)

I guess I'll contact Fyne Audio too. After all, their speaker are fairly new in the market, not much "mix & match" to be found yet.

I think the MAC might be a good choice for you, assuming you live in the US, where they can be serviced forever, but more because they have tone controls that can be very important in tuning the sound to your taste for individual recordings. Heavy rock and metal are often mixed with different priorities than acoustic music, so it’s really nice to be able to get the sound where you want it. It’s not so much of what is a "better" amplifier. Think more in terms of what suits your listening tastes. It would also be a good idea to arrange a home audition, which any decent Mac dealer should do for you.  Same with any of the high-dollar amps you are looking at.  Service is included in the dealer's margin and the customers of high-ticket items have every right to avail themselves of what they are paying for.  

Thank you for your reaction @chayro . I'm alas from Europe. Which also means the price of a McIntosh is 150% of the USA. (MA9000 = 11.000 USD => more or less 9.500 EUR ; retain price here is 14.200 EUR = more or less 16.500 USD). I bet it's the same the other way around, for EU audio brands.
I'm looking at second hand, it's the part of my system I didn't settle yet :s

Any further thoughts on your speakers after living with them a few months? What amp did you settle on?
The Fynes are interesting speakers, but since they are fairly new, there isn't much user feedback yet in the forums I've read. Thanks in advance for your thoughts.

Hi @waltersalas ,
Reading the feedback about McIntosh, I started digging deeper on shipping requirements and after care. The unsettling higher cost finally tipped me over to look further, for a more local brand.
Eventually, I went for a German brand: T+A. Their PA 3100 HV (A+B integrated amp) has excellent reviews and I could buy one for a fair price. As the enclosure was damaged way beyond the dealer’s promises, he had it completely replaced at T+A. They showed an amazing customer service - excellent open and transparant contact.
While I started on a BlueSound node, I meanwhile bought a brand new T+A MP 3100 HV as well. Very multifunctional and highly integrated with the PA.
The speakers work awesome now. They have not blinked an eye, the looks are truly gorgeous and stunning. I replaced the spikes with GAIA I feet and put them on a 30 kg marble slab (my wooden floor is not that even). My dad brought Pink Floyd with him last week, to test the Mediaplayer with the Amp. The depth of the sound is amazing, you can point where the instruments are played. I used to listen to music, now I really take an entire evening to listen to this setup. Fyne did a great job with these massive speakers.

My complete setup
- T+A PA 3100 HV & T+A MP 3100 HV (both on an oak slab, supported by Herbie’s Big Fat Dots to avoid damaging the closet on which they stand).
- T+A Quad XLR interconnects, standard powercables but I plan to move to T+A Carbon. WireWorld UTP cable.
- Fyne Audio F704, on Gaia I feet.
- Pure silver bare bi-wire cables from Tempo Electric (USA)
- REL Carbon Special, on Herbie’s gliders, connected with the REL AirShip.
- iFi Audio PowerStation to clean the electricity

(If my wife reads the above, you're all invited to my funeral)