As a long time B&W owner and fan several points.
1) As good as the Signature series was the D series are much better, specially the 2nd generation "Diamond". It has many upgrades over the 1st D. Check it out Bo1972.
Cabling makes a difference as well. And give them time.
2) The Rotel are not a match for any speaker in this class.
I am not a fan of MAC with the Diamonds.
The only Classe I like are the current generation monos with the B&W.
I think the Pass Labs class A amps sound great with just about any speaker. But the B&W, as efficient as they are, really like a lot of watts or amperes to sound best. So a new Pass Labs might be out of your budget.
Other possibilities are Spectron (Monos), Spectral, or the new Hypex Ncore Amps. There are two versions, a DIY NC400 and the OEM NC1200. I have heard both and own a NC1200 by Merrill Audio. If the OEM is out of your price range the DIY is very easy to assemble. They are class D but are competing with the best of Class A A/B in and above its price range. I will say that when I had the NC400 in my system it made many a fellow Audiophile Club members say wow. However when I put the Veritas by Merrill Audio in my system it was the first time the full potential of the 802D speakers showed itself.
Now we all have our likes and dislikes. Some like a warm sound and others want a transparent and others a dynamic sound etc. The Hypex Ncore will make music.
So try in your system, if you can, anything you want to purchased.