As someone who imports and sells a line focused on current vs. wattage, I
have a POV. Art Audio amps are biased toward current. That is, our amps
are high current and deliver lower wattage vs. many of our competitors.
This means that with any given tube, we could deliver a much higher
wattage number but opt against it.
This absolutely does allow
for better handling of lower impedance speakers. But that is not the
only reason and it is not just marketing.
The extra current
delivers better frequency extremes. You get lighter & airier treble
with better nuance and detail. Bass response is tighter and more
refined. Maximize wattage in SET or Push Pull triode and treble gets
rolled off and bass gets flabby.
Most of this is false. Current does not exist without voltage; further, wattage does not exist without voltage and current. IOW you can't make one (current) without the others (voltage and wattage).
Similarly, extra current (if it were somehow to exist) does not affect bandwidth. What **does** affect bandwidth is output transformers; generally speaking the bigger you make them the less bandwidth you get. In voltage amplifiers if you can't put enough current through the tube you might lose some high frequency bandwidth; that is why 12AX7s are not a good input tube to use in a power amplifier unless bandwidth isn't important.