Before you determine you don't have enough power, step back a minute and look at all the variables.
How loud will you be listening? Amplifier power has a logarithmic relationship to perceived loudness. The amp has to crank out ten times the power for you to double the volume.
If you are listening at medium or lower levels there are very few speakers that need massive amounts of power.
The Era D4 speakers show a nominal impedance of 6 ohms which shouldn't tax your amp. The specs list a sensitivity of 84 dB with 1 watt of power; while this is somewhat low sensitivity, 84 dB is actually a pretty fair listening volume. With 50 watts of power on the NAD, you'll have quite a bit left in reserve.
I use a Trends 10.1 with about 7 watts a channel for a pair of LS3/5a clones which are similarly low efficiency. While I use them as near-field monitors for audio editing work on the computer, power has not been an issue for me.
However, if you're after rock concert volume levels, I'd suggest you need to rethink the whole system.
How loud will you be listening? Amplifier power has a logarithmic relationship to perceived loudness. The amp has to crank out ten times the power for you to double the volume.
If you are listening at medium or lower levels there are very few speakers that need massive amounts of power.
The Era D4 speakers show a nominal impedance of 6 ohms which shouldn't tax your amp. The specs list a sensitivity of 84 dB with 1 watt of power; while this is somewhat low sensitivity, 84 dB is actually a pretty fair listening volume. With 50 watts of power on the NAD, you'll have quite a bit left in reserve.
I use a Trends 10.1 with about 7 watts a channel for a pair of LS3/5a clones which are similarly low efficiency. While I use them as near-field monitors for audio editing work on the computer, power has not been an issue for me.
However, if you're after rock concert volume levels, I'd suggest you need to rethink the whole system.