b&w n vs d money better spent on amp?

I replaced the plastic phase plugs in my 805Ns with solid copper ones, which brightened the sound and evened the amplitudes over the dynamic range. With the Cu plugs I find the 805N to be superior to the newer 805S, which I compared intensely back-to-back over 3 hrs in a listening room.

Perhaps you can find some simple, inexpensive tweaks like this for your 802Ns that will bring them closer to the qualities you like in the 802D.

If you stay with the N series and spend the saved money on better amps, then you will wish you had the diamond series. It's a catch 22.