Hey, I got the D15’s several months ago based on Shady’s review, and got the D5C for a sonic/visual match, so I can at least give some subjective impressions. I am powering a 5.2.4 Atmos system with a Denon 4500, which has no problem driving all my speakers loud enough to cause hearing damage! So I doubt the 87 sensitivity of the D17’s will be a problem for your Denon.
As to the sound quality, both the D15’s and D5C sound fantastic to my ears. Very detailed but still smooth if that makes sense. The MTM design of the D5C should not sound good much off axis, but I don’t really notice much of an issue even sitting in the outside seats. The tonal balance of the Demands is similar to the Revel Performa series to my ears, but just a little brighter - but not forward or harsh like I find the Martin Logan new F-Series towers.
The combination of looks, sound quality, and build quality is really amazing for the prices these are going for now. Unless you need THX reference volume in a large space, like Shady says, you would be crazy not to grab these along with a D5C. And BTW, the 85/105 DB reference standard is only for large commercial cinemas. UHD and Blu Ray discs for home use are mastered for a lower reference of 76-82 DB depending on room size per SMPTE studio guidelines so the need for high sensitivity speakers to hit “reference” for home theater may be overblown in many cases.
View attachment 65783View attachment 65784