Is more amp power always better...?

Definitely not always.  We also can't really say this is true about having more damping factor. 

The amp/speaker match up is important as is the quality of the first few watts of power.   There are definitely speakers with troublesome impedance curves that like big amps with low output impedance, but also large speakers with big woofers that can benefit from high output impedance.  See Nelson Pass's writing for the latter.

So the ASR Emitter 1 might be a good option. I own the ASR Emitter 2 Exclusive and they sound great with a pair of Quad 2905’s. Quad 2912’s would be the same. I have to share with you however my experience when I matched the ASR with a pair of Monitor Audio GS 10 bookshelf speakers. The amp was just too much for the bookshelves. It sounded like a Tasmanian Devil was trying to break out of the cabinets. When I bought the Monitor Audio’s I was told that it was impossible to blow them up but I blew both a woofer and tweeter. I then paired the Monitor Audio’s with a Rega amplifier and they were fine.

The numerical value given for damping factor is 8 divided by the output impedance of the amp—the lower the impedance, the higher the damping factor.  A typical SET amp can have an output impedance of 2 ohms or more, for a damping factor of 4 or less.  This relatively high output impedance interacts with the impedance of the speaker, which varies with frequency, and thereby affects the frequency response of the speaker (the lower the speaker impedance, the greater the change in frequency response.  Thus, SET and other tube amps with high output impedances are best used with speakers with a rated impedance of 8 ohms or more, and with an actual impedance curve that is relatively flat.  Any damping factor above 8 is probably high enough to be irrelevant.

My thinking, a speaker having a true 89dB sensitivity to be used in a 10'x11' room can easily be by served by an amplifier providing 50wpc at 8ohms and 100wpc at 4ohms. 

My advice, search for an amplifier that mates best towards the presentation you desire rather than the power it delivers. Low watt SET amps an exception.  

Late again, but some thoughts.

Never buy just "watts." All watts are not equal. I would want something with good wattage, outstanding ability to deliver current, and the amp is not ’cool-sounding’ or ’warm-sounding.’ I’d want musc to sound like what is engraved on the record, NOT the amp adding its own colorations to the sound. Besides, the more ’personality’ an amp has, the more your music is going to sound alike, and nothing will surprise you any more.

People seem to think merely getting enough watts insures the best sound. That is a poor choice for determining sound quality. "Enough watts" does not mean that it can also make voices still sound ’delicate’ or ’poignant’ when required. Sometimes, the end result is less than one hoped for.

The qualities of sound are something a designer aims for when he/she is designing the amp, and not all amps have it. I’ve owned the Goldmund (Mimesis 9, Jadis Defy 7, Vtl 300s, Plinius SA 250, VAC Renaissance 70/70 and a few other of the ’super amps’ so I’ve realized that the amp that might be best in the high frequencies (the Goldmund) doesn’t necessarily do the ’quiet moments’ as well as, say, the Defy 7 did, or the 70/70. Or even the VTL 300s (no slouches!). But it took considerable experience (and money) to realize that no amps (or anything else!) ’had it all.’

The only component I have no complaints about is the ASR Emitter. It sounds similar (but not all the way) to my Antique Sound Lab Hurricanes, in that it does at least ppp to ffff, can sound delicate, poignant and heartbreaking when one is listening to a flute solo. It can sound bombastic, as when playing Stravinsky’s Rite of Spring. And it can rock out as in the Rolling Stones’ ’Gimme Shelter.’ And it does this while doing the unlikely solid state characteristic of having images with focus and true three dimensionality to the images, which is very hard for solid state to do. And it is a very high resolution device, which the Hurricanes, even with their nothing-short-of-astonishing realism, are merely ’good’ at.

So, one has to think about what qualities in sound are their highest priority, and then look for an amp, once you know what you value in reproduced sound.