I spoke with a KEF Blade and KRELL amp dealer today on the East Coast. The dealer loves the KEF Blade and knows it very well. We had a superb conversation about amps for the Blades. One of the most knowledgeable dealers I have ever spoken with.
He said that in his experience the Blade Meta is a bit more detailed, a bit faster sounding, and tighter bass than the older Blade. However, he has an older Blade that they have in the shop and he wants to keep that for himself. He said that the changes on the old Blade to new Blade Meta are not that big. He did say the changes from old LS50 to the new LS50 Meta are much bigger sonically.
In terms, of amps he loves the new KRELL XD amps on them. the DUO 300XD model and up (unfortunately I have the lower power DUO 175XD). He also said the CODA #16 is great with the Blade (does not sell CODA).