I have Spendor A5 . It requires a lot of power , ideally i think it requires 100+ Watts . Lot more dynamic when I tried with top of the line symphonic line integrated and Cyrus seperates.
I am not sure if Sudgen would pair better. But some vouch for Sudgen Mystro + Spendor combination and i see some folks use it with Spendor A6 which is even harder to drive . Looks like more natural sound compared to Naim
Can you PM me the price you paid for the Sugden Mystro