Is more amp power always better...?

Some designers claim that paralleling multiple output devices to get higher output degrades the sound.  The original Dartzeel amps were based on the philosophy of minimizing output devices (only two were used per channel), but, demands from the market for more than 100 watt/channel made them abandon this philosophy. I don't know if there is any truth to this claim.  But, many years ago I heard two Rowland amps that were very similar in design, but one was rated at something like 50 watts and the other 200 watts per channel.  Both were used to drive somewhat challenging speakers (if I recall correctly, they were Maggies).  At the not extremely loud volume I heard the combinations, I actually preferred the lower powered amp and so did the owner of the store that demonstrated the amp/speaker combination.  Who knows what other factors might have been involved, but, in this case, the lower powered, and cheaper, amp prevailed.  

When coupled to high efficiency speakers, my favorite amps are almost always low-powered tube amps  I currently run a 5.5 watt per channel pushpull pentode amp.  My other amp is a parallel single ended amp that puts out a whopping 6.5 watts per channel   One of my all-time favorite amp is a pushpull triode amp that I think puts out 8 watts per channel, my other favorite is an output transformerless amp (giant four box affair for stereo) that puts out something like 30 watts per channel.  

@dunkin The most important thing is that the amp have good clean reproduction at a low power level like 1 Watt because even with your speakers that will be a common power level.

The class of operation, the amount of power isn't important as long as the amp is musical and plays nice with your speakers. As a general rule of thumb its not a bad idea to have a bit more power than the speaker needs so you'll always have headroom. So if the speaker's max is 70 Watts a 100 Watt amp is a good power level.

You can convert RMS wattage ratings to current (amperage) easily enough but that isn't the entire story wrt the quality of the power supply, which is important in supplying short term peak power without distress.  Making sure to have sufficient peak power for dynamic musical passages is probably why Ralph recommends exceeding the speaker's rated wattage.  However, I don't always trust those "ratings", which is why the SPL calculator I posted can be useful to evaluate power needs for your specific speakers and room.

Good point on doubling power into lower impedance loads but those numbers get played with by manufacturers too.  Take an amp rated at 200wpc @ 8 ohms and 400wpc @ 4ohms, does that amp really double into 4ohms, or is it actually a 250wpc amp that provides 400wpc into 4ohms?  Does it really matter?  Simply purchase an amp that is large/powerful enough to drive your speakers to the levels you want to listen on the music you like to play.

When I think about "quality watts" as discussed here, I am reminded of the Lamm 1.2 Reference amps that I owned.   Those Class A hybrid amps were rated at only 110/220wpc into 8/4ohms, when set to their high impedance setting, and the same wattage rating into 4/2ohms when set to their low impedance setting.  My speakers dip to just below 4ohms at certain frequencies and those amps definitely sounded better at the low impedance setting in my system.  They were not powerful enough to convincingly drive my speakers to the SPLs I wanted to hear but, within the volume levels they provided, there seemed to be no loss of dynamics or tonal color.  IOW, they sounded really good, but simply ran out of steam at a certain volume level.  I have never heard another amp respond like that in an underpowered situation.  Most I have heard begin to sound stressed and thin well before their limit. 

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.