Every 3 dB of improved efficiency cuts the power required by half.
Most tube amps can drive 4 Ohms, but they are sensitive to variations in the impedance. Examining the impedance curve can help find things to watch out for.
See the black line in the very first chart for a typical example of how a spaeker's complicated impedance can interact with a high output impedance amplifier (typically tubes):
https://www.stereophile.com/content/balanced-audio-technology-vk-56se-power-amplifier-measurements
Best,
E
Most tube amps can drive 4 Ohms, but they are sensitive to variations in the impedance. Examining the impedance curve can help find things to watch out for.
See the black line in the very first chart for a typical example of how a spaeker's complicated impedance can interact with a high output impedance amplifier (typically tubes):
https://www.stereophile.com/content/balanced-audio-technology-vk-56se-power-amplifier-measurements
Best,
E