Nothing like a new great sounding stereo toy to make your day! I spent about an hour & a half serious seat-time with those speakers powered by the new Classe Delta stack. Very nice, indeed. Also spent about as much time with the Aria 936 powered by a McIntosh MA5200 and a Luxman integrated. The 936 provide a little more bass and more accuracy & definition in the lower frequencies. Focal makes some truly nice speakers. Congrats and enjoy!

Outstanding deal on those Focal! Congrats! Before you buy the MAC MC152, make sure your NAD pre will be a proper match for it. Also, keep in mind that MAC rates it's products very conservatively. So, that 150 watts power rating for the MC152 is probably higher and even MAC says they don't really know what the real THD is. They just went with their usual 0.005% for the hell of it. Independent bench testing on that amp found the THD to be something like 0.0000?. What distortion? You can't go wrong with MAC. You can go different but you can't go wrong. Full disclosure: I love my MAC! After you get that MC152 or something roughly equivalent, I see upgraded speakers in your future. No knock on those Focal but with an amp like the MC152 you're going to be wondering about playmates for it that are in the same league. Just sayin'.

When you talk about "open top end", I'm assuming you mean the higher frequency ranges (e.g. 2 kHz to 20 kHz & up). Humans generally can't hear anything above 20 kHz and this gradually becomes more compromised as some people age. Anything above 20 kHz is strictly feel. I have no doubt a MAC amp will provide all the "open", accurate and undistorted "top end" you can handle. The tweeters in your Focal will have a lot to do with this. In my opinion and experience, speakers are the business end of any sound system. If your NAD pre-amp doesn't get in the way, the MC152 will give your Focal everything they are designed to handle and then some.

I've spent a fair amount of time with the Focal Aria 926, powered by that monster Classe Delta stack I mentioned earlier; a lot more power & juice than the MAC MC152. At the time, I was A/B'ing your Focal with a pair of Monitor Audio Silver 500 and, then, a pair of the Silver 300. A friend I was with, at that time, thought the Focal were a bit forward for his tastes but I didn't. I thought they were very nice and every bit as competent as both the MA, from upper bass on up to the higher frequencies. As I recall, I also thought they maybe might have been just a smidge better at handling brushes on cymbals and drums. On the flip side, however, both my friend and I agreed the MA were a little tighter and more accurate in low bass response. Comparatively, the Focal were just a little muddier down there; less tight, less accurate. However, you really had to be in critical listening mode to pick that up. I'm guessing this could be a factor of the bottom port design. My ears thought the Aria 936 were much better in this regard.

I don't have a lot of recent up close & personal experience with NAD equipment beyond some critical listening I did seven years ago when I was shopping for a CD player. I auditioned 2 of their higher end players and thought they were very flat, which is to say relatively accurate. However, compared to a Marantz I eventually purchased, neither one of them, even the one that was, as I recall, around $150 more than the Marantz, were nearly as musical. Based upon reviews I've read, audiophile friends I've spoken with and my own limited experience with NAD components along the years, my impression is that a flat, accurate response seems to be one of their hallmarks. This sound signature obviously appeals to many audiophiles. Otherwise, they wouldn't be as highly regarded as they are and have been for so many years. I mention this because, sonically speaking, I have no idea how your NAD pre-amp might pair with the MAC MC152 or any other amp you are considering but I do think it is important to factor that in to your deliberations. Component matching, I believe, is a very important consideration.