Why tube amps are rated so low, still don't get it

Wow, Thank you Mr. Porter for the fine post!
Regards,

There are lots of good speakers that will give you very satisfying results with 50 watts of tube power in a moderately sized room. Though I'm not familiar with either of the two speakers you are considering either appear to be quite adequate. I'm using 90db floorstanders at home running them with 10watts of PP (tube) power and that system can give clean sound loud enough to disturb the neigbors next door. The two speakers you mention also boast 90db efficiency. Keep in mind also that synergy is not just whether the speakers will play music at a satisfying volume with the given amp. The best thing you can do to determine whether you'll like it is actually listen to the specific combination of amp and speaker you are considering. If that proves difficult, buy used, listen, and sell if you don't like what you hear. Repeat this procedure till you find the combination that raises the hairs on the back of your neck and gets your toes to tappin' involuntarily, OR until your wife/s.o. throws you out of the house on your ass!

Marco

50W is pretty hefty for a tube amp. Nobody can look at a set of specs and tell you whether a particular amp can drive a particular speaker. (All right, a 200-watter can drive horns.) There are too many variables. The only way to know for sure is to get them both into your room, and play them as loud as you are likely to ever want to listen with some really demanding (think orchestral warhorse) material. If it sounds good, it is good.

Hi There,

I'l be honest with you - Shanling is not available here. I tested out the CD Player when I was overseas and fell in love with it, so I imported it specially. The tube amps I will thus not be able to test.

All we're trying to explain is delivered power to a visible by amplifier freequencies.
A noise contains all components of such audiable "visible" freequencies.

If we take a trivial sine wave 1kHz and feed to both 50W tube amp and 50W SS amp they will both deliver the SAME power to the dummy load(measured by true-RMS Voltmeter).

Speaking of the noise noise experiment we may assume all audio freequencies but far not all load combinations.
We also can apply the term of "visible" freequencies and in SS case they're much larger let's say at particular THD limit set for both experimented units.

Now, in your case when you're shopping for full-range speakers of medium efficiency... I'd have to say you'll only hear half of them with 50W of tube power. I'm not saying that you shouldn't shop for tube amp that HAS plenty of advantages to the SS but you'll have to shop for higher powered ones than 50Wpc.
You must also take a note that higher power tube amps have a higher-complexity power supplies and so with cost of parts and lower reliability.
I have a tube amp myself and it took me a while of research how to improve a reliability without loosing performance and I finally did it at once. I now prefere in bi-amp setup together with Sunfire Symphonic Reference unit fed trhough DIY balanced converter with adjustable gain -10 to unity.
It saves the tubes and brings me the best of both worlds of amplification FYI...