NAD seem to work on quite long product cycles. I don't think the C326BEE needs replacing yet to be honest - it still competes with newer amps like the PM6004 and it is quite nice to see a company with a stable product line.
good to see you're enjoying a pair of Dali Zensors now. I use mine for 4 or 5 months now and they sound way too good for the money. Awesome natural sound with lots of detail.