My take - the more efficient the speaker, the more the balance shifts toward quality from quantity when it comes to amplifiers.
For a given budget, any amp designer is going to have trade-offs between power and finesse. There are obviously going to be some designers/companies that are more creative/efficient, etc. but building a more powerful amp means higher voltage parts, bigger transformers and caps, bigger heatsinks, larger chassis, etc. which take budget away from higher quality components.
In other words, high efficiency speakers do not, in the least, diminish the benefits of a high quality amplifier, but they do reduce the need for tons of power. If anything, a high efficiency speaker will expose the limits (noise floor, linearity, etc.) of your electronics much more readily than a low efficiency speaker.
If you've got high efficiency speakers, take advantage of your lower power demands to get an amplifier with more refinement for the same budget.
For a given budget, any amp designer is going to have trade-offs between power and finesse. There are obviously going to be some designers/companies that are more creative/efficient, etc. but building a more powerful amp means higher voltage parts, bigger transformers and caps, bigger heatsinks, larger chassis, etc. which take budget away from higher quality components.
In other words, high efficiency speakers do not, in the least, diminish the benefits of a high quality amplifier, but they do reduce the need for tons of power. If anything, a high efficiency speaker will expose the limits (noise floor, linearity, etc.) of your electronics much more readily than a low efficiency speaker.
If you've got high efficiency speakers, take advantage of your lower power demands to get an amplifier with more refinement for the same budget.