Amp. rec with major restriction

[jonedd]

Lately I've been playing around with various designs for some of the Markaudio FR drivers. I've noted some of the amp recommendations, many of which are tube amps. I'd like to try one out, but I'd pretty much resigned to Class D because this summer I plan on installing solar for my house and I need to keep power consumption minimal.

Are there any tube amps that have relatively low power draw and still sound nice? Does anyone know the power consumption of a typical low power (3-6W) tube amp?

This topic is kind of grey for this forum vs. the tube amp one but good matching with the speakers is more important me than anything engineery