Hi, Stephen,
I believe you'll have to provide some specs to get a definitive answer - even from Hugh ("Mr. AKSA") Dean. Like:
* what power is the NAD2600 - ie. X into 8ohms, Y into 4ohms?
* what is the instantaneous output current capability of the NAD2600?
* what efficiency is the KEF 104.2 speaker?
* what efficiency is the KEF Q-9 DS speaker?
* what efficiency is the KEF 202C speaker?
I believe you'll find that the AKSA 100 Nirvana will:
a) drive your speakers better, and
b) make them sound much better
than the NAD2600.
Regards,
Andy