@bop333 -
Supposedly: your current speakers are fairly sensitive, at 92 dB/1W/1M.
Many SS amps will safely double their 8 Ohm output wattage ratings, into a 4 Ohm (nominal) load, which your speakers will present.
According to the specs: your NAD doesn't, staying at 80 WPC, into both 8 and 4 Ohms.
You might try a 200 WPC @8 Ohm amp, that you've confirmed will safely handle 4 Ohms (preferably: double it's output), with your Triads and see if they satisfy, prior to making any other leaps.
If not: more efficient speakers may be your ticket.