NAD D3045 vs NAD C268 for KEF LS50 - which amp for greatest synergy with KEF LS50?

The C326BEE is a Class A-B integrated amp, while the C268 is a Class D power amp. Two very different animals. The D3045 is also a Class D, but integrated and has a DAC that the C326BEE doesn't have.

You might look for a C356BEE, which is a little more powerful and has the "MDC" modules available should you want a built-in phono amp or DAC. The new PP375 phono amp is quite good, and selectable MM or MC settings. If any are still available (my dealer had one last time I was there), they are barely more than the C326BEE and half the cost of the 150w/ch C375BEE. My cousin got a demo model C56BEE from that same dealer for $700, with the DAC module installed.

I have the NAD 356BEE in a second system. Previous to that I also owned the 326BEE. I made the swop for the extra power. Just enough to make it easier driving some speakers. The LS50s would probably be better served with the extra 35 NAD watts. 

I'm running my LS 50's with a recapped Threshold 400A. They sound effortless. Find a good class A amp with plenty of power.

I also use the new NAD M10 With KEF LS50s in my home office.  Very nice integrated amp/streamer/DAC and perfect for my small room.