Typical Characteristics of a McIntosh / B&W system

I've owned high end McIntosh (always receivers, not separates) and B&W speakers before. Sold my last setup 4 years ago when I moved to a small apartment.

I'm finally in a place where I have a listening room, so I recently bought the McIntosh 6700 receiver and B&W PM1's. It sounded great in the store, but sounds mostly like crap at my place. It's WAY too bright. Sounds decent at low volumes, but if I turn up to normal listening levels or, heaven forbid I go to 11, it becomes unlistenable.

I'm sure my room plays some factor as I haven't treated it yet, but my $450 AudioEngine's sound amazing in the room and this $12K+ setup sounds like crap.

I will say that when I auditioned the McIntosh/B&W's in the store, I realize in hindsight that I listened to a lot of acoustic-y music. Even at home, the set up does ok with that style. But everything else sounds pretty crappy.

Perhaps my ears have gotten overly sensitive to music on the brighter side. Or maybe this receiver or McIntosh in general are skewing their sound to be overly bright/revealing/clean etc.

Any opinions on this? Are McIntosh/B&W setups known to be overly bright?
I really don't like B&W, but I have heard them with McIntosh many times. I thought it was one of the better sounding combos for B&W. For me, I've always found the highs too bright/harsh.

I'm sure you already know this but you have to make sure everything is broken in. That could very well be the problem.
The typical listening environment is not conducive for critical listening. For general music, yes; however, if you want to obtain absolute clarity without speaker-room interaction anomalies, then you must treat the room. Unless you treat the room, your apt not to hear the true benefits of your system, no matter what the components are. Having experienced a fair share of speakers and amps over 35 plus years; I learned from trial and error that most of the time the smallest amount of room treatment and proper placement of speakers allowed for an ideal listening session. Of course, some components will consistently portray a unique trait that is hard to mitigate due to individual sensitivities and listening tastes.

I have used B&W's for the last 15 years and have not had the purported listening anomalies that some people claim due to me using proper speaker placement and using room treatment. The new P1's due to their smaller size and accurate tweeter are apt to beam, that is why you are hearing the sound portrayed the way you describe. It is possible that the listening room at the demonstration studio was treated or had furnishing, carpet, curtains, etc., that may have influenced the sound.

I personally believe that once you do at least minimal room treatments, you will find almost any speaker to sound better, pending your own personal listening tastes.

You have nice components. They sounded great when you auditioned them but in the showroom. So time to explore your room. And experiment with placement of your speakers relative to your listening chair.

You already said the room is not treated. Its impossible for us to know what this means but I am guessing you have hardwood floors along with windows and a lot of highly reflective surfaces. If so, add some throw rugs, heavier furniture, drapes, etc.

Finally as Audioquest4life points out, the design of the PM1 would make the speaker prone to beaming. So take a serious look at how they are positioned. Forming an isosceles triangle, where the distance the speakers are from each other is less than the distance of the speakers to the listening chair is a good place to start. Set them up in this arrangement and start making minute adjustments, a inch or so at a time. You'll be surprised how critical placement is with good 2 channel like what you have. Good luck.
Friend is running a Mac integrated, cd/sacd player with B&W802 Diamonds and they match great. It is likely you are dealing with a room issue more than anything. I use B&W800D and recently moved. My new room initially had no bass (opposite of every other room I have used). Placement is key but the room plays a huge role. My speakers are closer to the back wall than I would have preferred and I have added some room treatment panels with significant effect.
My experience, with the McIntosh 6600 integrated is that it took awhile to break-in -- I have had mine for 8 months and its sound is still improving. Give it time. I couldn't be happier with my purchase.

The link below describes a similar experience to yours with the MC452 which, when broken in, lost its initial brightness--replaced with all the beauty that McIntosh is known for.

I hope you enjoy your great new gear!