Then there were 2

There are 2 woofer in each cabinet. The woofers themselves are 90db. but with 2 in parallel it is higher but I dont have exact measurements of efficiency. speakers are 4 ohm.

@jimbones Tube amps do not double power as impedance is cut in half. That is why efficiency is a more useful spec than sensitivity when tube amps are involved. In this case, while sensitivity does increase, the efficiency remains the same. Since the total wattage of most any tube amp is lower into 4 ohms, I think you will find that you simply need more power.

I would also consider putting the woofers in series rather than parallel. They will act the same in the enclosure although you'll have to change your crossover a bit. But a tube amp will thank you as it will make more power, have wider bandwidth (particularly in the bass) and make less distortion.

@atmasphere good point, will do. Or maybe just make it a 8 inch 2 way 8 ohm speaker.

@jimbones Well then its 8 ohms, but the efficiency in all cases remains the same. I think you're better off with the dual woofers, because you have more surface area for making bass and less excursion. Putting them in series works great for tubes.

Ref 75 SE over QS 120mono over the Rogue 
I started with Rogue  when I upgraded it was between Ref75 and Aesthetix Atlas went with Aesthetix 

Enjoy the Music 
Tom

QuickSilver V4’s over the ARC, I have first hand experience with both brands and value QS is a no brainer but also a very good sound and super reliable.  My GS150 was short lived and quality with the new ARC is questionable along with customer service.  I have friends that are dealers for both and QS is their pick to own.