Is there any truth to this question?

IMO, the only indisputable comments so far are Pubul57's:

****I have concluded that lower power versions of the same circuit sound better than those iterations with higher power if the power is sufficient to play at a volume you are satisfied with in the room you are using.****

and Tom6897's:

****Absolutes do not exist in audio only in Vodka:-)****

Digepix, to address your question specifically: If the YBA's 50 watts is
sufficient to drive your speakers EFFORTLESSLY, then wether 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. Yes, it's true that there is no point in buying more power than needed, but the problem is that what is "needed" is often underestimated.

While I disagree with Mapman's suggestion that digital handles transients better than analog (and this is not meant to start yet another digital/analog debate) I think he makes a good and very important point about the issue of power reserves and dynamics.

We tend to focus on this issue, and how it relates to clipping, in terms of it's effect on the "sound" of the music and the onset of audible tonal/harmonic distortion as the amplifier approaches clipping. We tend to overlook the distortion of the dynamic flow of the music which is more subtle but just as important. Well before we hear any obvious harmonic distortion, as the amplifier approaches clipping there can be a diminution in the ease of the dynamic nuances in the music. There don't necessarily have to be a lot of transients in the music for inadequate power reserves to have an effect on playback. If the music is very complex as many orchestral works can be, with many instruments playing at once including percussion and loud brass, the effects of inadequate power reserves can be obvious. Sure, a good 35 watt amp can sound more pure and sweet than the 200 watt version of a similar circuit, but what good is that little bit of extra purity if (for example) when listening to a well recorded trumpet
with orchestra, it has natural and exciting speed and dynamic flow when playing pianissimo-mezzoforte (pp-mf), but as soon as the entire string section and percussion join in it sounds slow and compressed as the trumpet approaches what should be a real-life fortissimo (ff). It really puts a damper on the music, and I hear this effect wether it's vinyl or digital if the amp doesn't have plenty of reserves.