Is more amp power always better...?

I have a pair of very efficient speakers at 12 ohms impedance playing in a modest listening space and the best sounding amps are those of low wattage class-A.  I've heard a number of class-A and class-A/B on my speakers, even those of class-A/B with the first several watts in class-A.  With really good and well-designed class-A/B amps, usually their first several watts are class-A and for many speakers at moderate volumes don't exceed much past class-A..  I have two First-Watt class-A amps (10 - 20 WPC) that are quite articulate and have plenty of power to handle my listening levels.  That said, you will need more power than those can deliver for your 89-db speakers especially at higher volumes.  Also, it depends on how well the amp can supply current if the impedance is low.  If your speakers are a true 89-db, they are playing at 89-db with 1 watt of power at about a meter from the drivers.  That level goes down about 7db at the listening position to about 82-db.  When I'm listening, most times, I like listening between 85-db and 95-db.  Any higher in my listening space and everything starts to get jumbled up sonically.  Looking in your case at going from 82-db to say 95-db at your listening position, you have to have enough power to drive the speakers to that level and higher on peaks.  Thats a 13db listening range.  With your speakers 82-db at the listening space is 1-watt of power and at 94-db would be 16-watts.  I have read that to be safe, you should have enough power to drive ~10-db above your normal listening levels for peaks.  That would equate to about 128-watts of power/channel.  Let me preface this with some caveats...  That assumes you have speakers that are 89-db and generally run no less than 4-ohms minimum impedance.  You'd need an amp that can deliver a good, clean 128-wpc into an 8 or 4 ohm load.  If your speakers dip notably below 4-ohms, you'd have to make sure the amp can deliver enough current to get to the 128 WPC.  Please note that my information above is based on a number of assumptions.  I personally don't need much power as my speakers are 106-db efficient so are operating most of the time in 1-watt or less of power !  I can get away with flea-watt amps easily.  Good Luck on your amplifier search !  

I have a Hegel h160 but was looking to downsize. Found a Keces e40 and for its size, price and power, I don’t think there’s anything that can outright beat it for its SQ within its power limits.

I have had less expensive higher powered gear in comparison to it and it beats them in SQ. Close enough to the Hegel at the SPLs I listen at on my dacs, speakers and room at a fraction of the cost...and size.

Want smaller and lighter and I am getting it. Someday, I would like to try a van Alstine Set 120 though, among a few others amps, speakers and dacs but no interest any longer in spending on high dollar items say over $3K and above.

The Keces drives my Opticon 1 speakers without issue but would be wary of floorstanders of low impedance or speakers that drop well below 4 ohms, or if you need high SPLs, otherwise its fine and can compete with much more expensive gear. Getting marginally more power and/or performance will cost up to double the price, or more.

The Keces works well with all my other speakers too.  The hegel grabs the little opicons so much the bass doesn't come thru as well, just too much for that little woofer.

The SET folks say that the first watt is the most important. Some of them get by with 5 and I’ve heard even less. 
 

In other words, quality over quantity but you need enough to drive your inefficient speakers. 

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.