Raven Blackhawk LE... am I going to be disappointed?

Raven includes a high pass crossover in that amp which is ideal for your situation.

"High-Pass Crossover

This addition to the Avian series provides an extraordinary advantage when using a subwoofer. It frees the power amp from 65% of the load it normally has to bear. This is like tripling the power of the amplifier in terms of its ability to drive speakers. It also frees smaller speakers from reproducing low bass frequencies that they really don’t reproduce very well which lowers overall distortion. This is all achieved with a gentle 6db per octave slope making it easy to achieve a seamless transition with a good quality subwoofer."

Try it, if you don't get enough volume or enough bass, just use the built-in crossover to a self-powered sub, that let's the Raven act like one of the big boys!

https://www.ravenaudio.com/product/blackhawk-mk3/

I am using a Luxman 10 wpc with wharfedale 87 sensitivity very happily in my small office. A crossover and a self-powered sub for a bigger room would be dandy.

For a main system, I recommend 2 subs, front firing, located adjacent to the mains to create/preserve imaging. It is both the fundamentals and their overtones that give location information.

chicagoblue,

Everyone is stupid for making low impedance speakers when they can design the same speaker with a higher impedance. Especially bad are wide swings. Now I am not saying that low imp. or wide swings arent sometimes the only way to create a design, but in almost every case, higher impedance, stable loads are much easier for all amps to drive and will sound better due to the ease on the amplifier. I can think of only one designer that may claim his amps sound better with low impedance loads. 

So you ask the designers of amplifiers about speaker design. Fascinating. What do the designers of toasters think, I wonder?   

Meanwhile, back in the world of sense and logic, we ask speaker builders about speakers. https://www.youtube.com/watch?v=tMAO9LPsups

I have had a Raven Nighthawk 3.1 for almost four months now. First tube amp I have ever had. I love it! Sounded good right out of the box. After a couple of conversations with Dave, I made a couple of tube changes. Now it blows me away. Speakers are KEF R3, not an efficient speaker. I have a medium size room. The Nighthawks 20 watts are pretty amazing. Plenty loud enough, plenty of thump. Someday I will move up the ladder, but I am enjoying my music so much now that it will probably be awhile before I do! Totally happy with Raven, Dave, and Jim. Great overall experience.