Normally Classe and NAD aren’t in the same league. Classe is much superior to the NAD especially when it comes to amplifiers. But in this case since you’re asking about the Classe Sigma series class D amp and I’m not a fan of class D amp. But for your B&W 802 D3 I would get the Classe Sigma amp. You should look for a used Classe Delta CAM 300 monoblock amps or at least the Classe Delta CA-2300 stereo amp for your B&W 802 D3. These Classe Delta CA-2300 & CAM-300 are class AB amps and are way better than the Classe Sigma class D amps. These Classe Delta CAM-300 monoblock amps will be ideal for your B&W 802 D3 and will do those speakers justice.
