I too have gone through this. I originally started out with C4’s, MC452 and a McIntosh C2500. Prior to the C4’s, I had a pair of B&W 804 D2’s. Not even close to the 800 D3’s, though I’ve listened to them and still preferred my C4’s.
The MC452 was absolutely not enough power for the C4’s. It sounded ok at low to medium listening volumes, but turn it up and you will begin to hear awkward upper frequency decay. I don’t want to mince words when I say decay, as it wasn’t decay in a literal sense, as in room interference. Almost choppy, but not distorted. I had GIK Acoustics design my acoustic paneling, so I do have sound treatment, but it wasn’t quite clipping either. I don’t know enough about the interaction of capacitance and voltage to make an accurate assessment of what was going on. When we built our house, I had a dedicated 20 amp line ran for my listening room and use Shunyata Research power cabling and conditioning, so I know it wasn’t for a lack of available voltage to drive the amp. Nonetheless, I can share from experience, I was not happy, at all, with the setup. The MC452 is not enough power for the C4’s. The monoblocks would be more than enough power to drive them. As for what the MC series amps sound like with Dyn’s, there are plenty of opinions and thoughts on it. Me personally, I no longer prefer the McIntosh amp sound, especially with Dyn’s.
At low to moderate volume levels, the combo just didn’t sound transparent and organic enough to me. Almost muddied with some music and I listen to a wide range from Miles Davis to Lamb of God.
I sold the MC452 and went with a set of PS Audio BHK300 mono blocks and they sound epically awesome now. I’ve swapped out the preamp with other makes, attempting to improve it and I didn’t find a better sounding pre, to me, in the $6k-$8k range. The C2500, I did swap out the tubes for a OE vintage set of Mullard’s, those paired with the PS Audio’s more than covers down on everything I like to hear in my music.
And reading Kot's post above regarding obsessive compulsive Dyn owners...it's true. The C4's take time to get into position and the toe in on them is the most I've seen of any speaker. They're not very efficient, so do require gobs of power and they can be sensitive to various other items in your signal chain, but they sound friggin' sweet once dialed in.
Happy hunting!