Is there any truth to this question?

IMO excellent comments have been made in many of the posts above, but with respect to the general question (as opposed to your specific situation) I would particularly emphasize these:

02-13-12: Frogman
If the YBA's 50 watts is sufficient to drive your speakers EFFORTLESSLY, then whether the Krell sounds better or not with those speakers doesn't necessarily have anything to do with it's higher power rating. It may simply sound better because it's a better circuit, or a better circuit for your speakers. Or, it may sound worse; but not necessarily because of it's higher power.

02-12-12: Grannyring
Extra watts and headroom can be a very good thing especially with large orchestral music and the like. Same is true for solo piano turned up to louder volumes.

An important variable is the kind of music that is listened to, and in particular its dynamic range (the DIFFERENCE in volume between the loudest notes and the softest notes). Wide dynamic range material, such as well recorded, minimally compressed classical symphonic music, can require vastly more power to handle brief dynamic peaks than small scale vocal, chamber, or jazz recordings, or dynamically compressed rock recordings. And even if a lower powered amp has sufficient power to avoid clipping on the peaks of wide dynamic range material, it may show evidence of strain on that kind of material that would not be brought out by material having narrower dynamic range.

On the other hand, if everything else is equal, more watts = more $, so investment of a given number of amplifier $ may result in higher amplifier quality if applied to a lower wattage design. But of course everything else is rarely equal.

In your particular case, I suspect you would do better with the YBA amplifier, based on your music preferences, your listening room size, and the comments about the specific amplifiers by Charles1dad (whose opinions I always have great respect for).

Regards,
-- Al

I was surprised at all the viewpoints this thread has generated. From a fact based scenario I'm am sitting close 1.5m from speaker, not ideal. I listen for the most part at 85-90 db maximum so at best I'm using 4 watts with my Vandersteens, correct? The 50W should give me 101 db to play with, way louder than I've ever listened to music at home. Could I reach the clipping point playing small group jazz? I like the YBA sound but can't afford there better amps besides a YBA 1 is only 85 W with more current. I guess I'll never know so I guess the best thing is to forget the audiophile rules and just enjoy the music.

Seems like you have a pretty darn good setup as is! As you say, enjoy the music.

Power is most likely not an issue with your nearfield listening position.

Devils in the details.....

86 db speakers are not very efficient. you may need more power to drive them vs more efficient speakers. So, to me, this conversation depends on the interaction between your amp/speaker cables and the speakers. That YBA amp may be absolutely wonderful matched with your cables and speakers. on the other hand, I don't know what db efficient speakers the amp manufacturer recommend that you pair with the amp. 86 db is on the ragged edge of making amps work too hard and therefore you may need proper power handling capability (i.e. huge power supply capacity) in order to drive less efficient speakers). All that said, turn it on, listen. Does it sound like the amp is working too hard? sometimes biamping with the same amp will fix this. other times, well, either more efficient speakers or better more powerful amp is required. If you are really concerned about this for your own system and not just an intellectual conversation, then go "borrow" a few more powerful, nice, clean amps within your price range, in-home test them with your favorite music at the listening level you are used to, and tell for yourself. A good stereo store will let you take home and audition. If they won't (even after taking your credit card information), then they aren't worth my time. I won't buy blind. Or, find a good friend and borrow their amps for a quick listen. or have a wine, dinner party with friends and have them bring their amps over for a in-home listening session. There are several fun ways to do this without buying first. But, 86 db speakers are not efficient. Far from it and they are difficult to drive. However, a class A Pass, Threshold, Mark Levinson (20.6, 23.5, etc.)amp at 50 wpc or more would not have a problem at all driving these speakers. I like the sound of YBA equipment (if you can find it), but I don't know about their load driving capabilities.

enjoy