Is more amp power always better...?

Amplifier power ratings: WPC in isolation is meaningless , it’s current (amps) that matters.

If your speakers are demanding to drive you’ll need a suitably muscular amplifier to support them.

Don’t look only at the headline power figure - see what happens when the impedance drops to four ohms. If the number nearly doubles, then your amplifier has good high current delivery and will be capable of driving more demanding speakers.

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.