I've MS Carnival 8 towers hooked up to a Norge 1000 Gold. I posted a review couple of years back - but unable to locate it now. Can't remember which thread it was.
Anyway, the MS Carnival 8s are laid back and mellow. IMO go well with a amp that has a brighter sound that you want to tone down a bit. I haven't heard NAD amps, so can't say about that pairing. They took the longest time to break-in, almost a couple of months. My wife says it is my ears that got broken in and not the speakers - she feels they sound the same and she doesn't like the sound, she prefers the brighter Carnival 6s. But I love the 8s and they are especially great for vocals and classical music. They can get real loud and have great low-end punch, I never felt the need for a sub.
I auditioned the Polk TSX-550T for our US home (I finally went with Infinity Primus P363s) but I thought the Polks sounded great. They were hooked to an Yamaha Avantage receiver and were playing latest hits (not my kind of music), and the sound was very clear and defined. I could clearly tell the improvement in sound quality and tone when we switched back and forth between the JBLs and Klipschs that were also connected to the same receiver.
My advice - DO NOT BUY the MS Carnivals without auditioning first. The sound is not to everyone's liking. On the other hand, the POLK's are pretty much universally liked and you cannot go wrong with them.
If you are looking for another option, I strongly recommend the Pioneer FS-51 or FS-52 designed by Andrew Jones. They sound really great - if you can get past their looks (the FS-52 are an improvement over the FS-51 ).
Good luck.
