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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
mapman's avatar
mapman
22,333 posts
 
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.

jdane
183 posts
 
My 91db speakers are driven just fine by my 20W tube amp.  (I will say, though, that with a similarly-priced SS amp at 40W, they sounded like sh*t.). I doubt that there's a general rule that you could follow that would trump the judgment:  "What does it sound like?  Do I like what it sounds like?"
russ69's avatar
russ69
3,520 posts
 
If you buy a lot of equipment over the years you will find out that consumer grade receivers at 100 wpc have trouble keeping up with 25 wpc tube amps. You'll also find some 60 watt amps that kill 100 wpc receivers. The difference is power supplies. Good power supplies provide great experiences. The best way to stay on course is keep away from consumer electronics and buy quality audio from know good specialty manufacturers. 
mapman's avatar
mapman
22,333 posts
 
The other things that make a difference in regards to how much power is needed is how loud will you go and how far away from the speakers will you be. 
onhwy61's avatar
onhwy61
5,236 posts
 
So much of it depends upon your room size and how loud you want to listen.  Obviously the larger the room, the more power you will require to fill that room.  The same for high volume listening.  If you are using a smallish room and never go louder than 80dB, then you really don't need too many watts.  BTW, 80dB while not considered loud is too loud to have a normal conversation.  The manufacturer's suggestion is a generalization to cover a wide range of situations that may or may not apply to your particular case.
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