how can low watt tube amps drive speakers with higher power requirements


I am new to hifi and I am super confused about something. Most audio blogs out there ask newbies to stick to amps that output power within the recommended range of the speaker manufacturers. However, on forums, blogs and even some magazine articles, I find pros reviewing tube amps with much lower output power (even in some cases 10-30W below the speaker specs) and find no problems. How can these low power tube amp drive these speakers? For example, the LS 50 metas spec sheet says "Recommended amp power: 40W - 100W) but I have seen posts here and on other forums where people will hook these up to tube amps producing as low as 12W of power at 8 ohms. Am I missing something?
selekt86
thanks for your response! this makes sense -  however, some literature out there also says that "low power" damages the speakers -  is there any truth to this?
Low power from the power amp or the Voltage/amperage from the power being supplied to your equipment? Lower volume should prolong the life of most any driver. Low voltage on the other hand is a death sentence for most modern equipment without some type of 120 vac maintainer... Surges are bad, brownouts are worse...

Regards
If you push an amp into clipping trying to eek out more volume from an undersized amp then you can damage a speaker. A monster sized amp means it’s still just barely ticking over at volume likely to make your ears bleed. You’re more likely to damage your hearing than your speakers with too much amp.

There are SPL meter apps you can download for your phone. Check how loud your typical listening level is. Add 10dB for dynamic headroom and calculate how much amp you need. There are calculators online to help you compensate for distance and room reinforcement. Be careful believing published specs. Sometimes they are optimistic. Also there can be adjustment for impedance and whether the spec is given as 1W or 2.83V (1W @ 8 ohm).
"Back in the day" we bought stereo systems and the first thing asked was, " How many watts?" Every manufacturer played the numbers game to perfection because we had become "spec sheet scientists". {RMS @ 8 Ohms 20 - 20000...THD 0.000001 S/N ratio. Wow and Flutter. You know the drill} Whatever....we used to kick car tires too. Tonight my kit blasts out a pathetic 20 watts per channel. It runs fairly high distortion levels relative to most. I only have two channels. Two speakers. No sub. One turntable. One CD player. Simple, endlessly astounding, intimate, a sound stage to die for, with totally lifelike audio reproduction, (IMO) I live in my happy place. Why did I take such a long route to achieve such an elusive yet rewarding destination? I think because I wasn't "listening" , I was measuring, counting, and competing. Just sayin' (Wish someone had told me that a long time ago)
No you are not missing something.
Any amp will work. It’s just a matter of how well and the results will vary widely.

The main thing always is to avoid clipping. That is public enemy #1.
https://en.m.wikipedia.org/wiki/Clipping_(signal_processing)
Tube amps typically soft clip as do some others.  You seemingly get away with fewer watts when soft clipping but the result is distortion nonetheless.