Pass XA 30.5 with Revel F 208 ?

Don_c55, while your calculations are correct, IMHO, it is not that simple unless you are listening to a 1K test tone @ 3 ft in an anechoic chamber. You must consider other factors like, actual listening distance and dynamic peak SPL for a preferred listening volume. I think the calculator in this link gives a more reasonable answer as to how much power is needed. Very easy to use, just plug in the numbers for an immediate answer.

http://www.allegrosound.com/Power_AllegroSound.html

Listed in Revel's specifications for the F208 is recommended power of 50-350. Obviously, it does seem that the F208 is better suited for higher power, however there is always an exception, as Cal3713 noted. Also, Cal3713's speaker has a 87db sensitivity and recommended minimum power of 100, while it's possible to find another 87db speaker with a recommended minimum of 10. So why? I believe it is due to type of cabinet, motor structures of individual drivers, number of drivers, complexity of crossover, and probably other factors. All of these require varying amounts of power to function at peak performance.

We are all certainly entitled to our own opinions, so considering the music Kartikeyp listed, classic rock, assuming at times, he may "crank it up", can't imagine that for background music, and classical, some having very wide dynamic range, I'm thinking speakers from Zu Audio. I have listened to a couple of Zu's with Threshold Class A, as you know a Pass design, and thought it sounded extremely good, at least to my ears, which from working in the audio industry for over 20 years, have heard many different components, speakers, and combinations. Also, have listened to other Zu's on different electronics, and they always seen to have the "live" musical character, which I prefer, as opposed to what I call a typical "hi-fi" sound.

So to answer the question in a general sense, when matching amp and speaker, I would always rather have a little more power than actually needed, as opposed to just barely enough.

Don_c55 and Charles1dad, I do agree that an excessive high level of AVERAGE SPL is for idiots, however there can be a very wide margin between average SPL and peak SPL with some music, especially classical. The SPL numbers to be used in the calculator I provided in the link are peak, not average. Also, this same calculator is found in many places on the web, as it factors in using a pair of speakers, room gain, and listening distance.

So how high can the peak SPL actually be at the listening position with a normal average SPL? Then please read the comments by Almarg, a well respected contributor to this forum, in this thread, especially the last paragraph of his 2nd post.

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1348838898&openusid&zzAlmarg&4&5#Almarg

Here is another paper worth reading about power needed and peak SPL in a "good hi-fi system",

http://www.daedalusaudio.com/images/loudspeaker%20sensitivity.pdf

Depending on the type music and quality of recording, it is very possible at the listening position to have a peak SPL of a 105db, while the average SPL is only 75db.

Bottom line is the required power is not for average SPL, but for that peak SPL, which is much higher than a lot of people think, even though it is only for a split second. Having less power than required for the peak SPL will restrict the dynamic range, and clip the amp for that split second.

I wish you the best in your sonic endeavors.

Charles1dad, thanks, and the same to you. Sorry for getting on the soapbox, but when I read this statement in Almarg's post,

For instance, I have many classical recordings on labels such as Telarc, Sheffield, Reference Recordings, etc. that at my listening position reach peaks that I've measured at around 105 db, although the average level during those recordings is perhaps in the low 70's.

it just fueled my fire.

No doubt everyone's goals and desires are different, however when matching amp to speaker, IMHO, too many people make choices that result in being underpowered.

BTW, your system, extremely nice, and such an appropriate name, I can only imagine.