Thanks for the clarification. I am assuming you just described as what I think of as headroom. (?). Is that right, or have I misunderstood that term as I interpret it in all my reading? Dynamic headroom? Extra power when needed for dynamic peaks? I am really not certain. Hope you don't think I' being sarcastic. I am only here to expand my knowledge and I'm not sure. I know I felt a little more confident with the extra 25wpc to pair with the 150w rated speakers.
Maybe you answered your own question about the Klipsch. An excellent deal, if you like horn loaded tweeter. I know some don't
I consider peaks as power demands that momentarily shoot up much higher than the average power demand. You can call them dynamic peaks too, I suppose. 25WPC more will get you 1.25 dB of SPL more, that is noticeable but won't do justice to 6 to 20 dB peaks typically found in music and movie contents.
Following is a numerical example to show how you can estimate your
approximate power requirements.
Assuming your ceiling height is not higher than 10 ft so your room size could be considered a little larger than "medium" size according to THX.
First, look at some known data:
R28F - impedance: 8 ohms nominal, sensitivity: 98 dB at 2.83V 1 meter, that is, 98 dB at 1W, 1m.
To listen at reference level (extremely loud for most people) your speakers have to produce SPL of 85 dB average, with maximum peaks up to 105 dB
Doubling power in watts will result in 3 dB increase in SPL (sound pressure level in dB)
Doubling the distance will result in a loss of 6 dB, but that's in open field
Depend on your room geometry you will get some room gain, it should be save to assume you will get at least 3 dB of room gain
Power requirement calculations:
Since you are supposed to get 98 dB at 1W, 1 meter, based on the R28f's published specifications,
To achieve SPL of 85 dB at 1 meter the speaker will need only 0.05W,
To achieve SPL of 85 dB at 4 meter the speaker will need 16X0.05W or 0.8W
To achieve SPL of 105 dB (that is +20 dB peak per THX cinema standard), you need approx 79.5W.
Now if you factor in the 3 dB room that we can safely assume, your speaker should only need 39.75W to get you 85 dB average and 105 dB peak SPL.
That's for one speaker, for stereo music, you will likely get the same SPL with only half, that is 24.875W.
Now assuming Klipsch exaggerate their sensitivity by 3 dB and their nominal impedance is actually 4 ohms instead of 8 ohms, then you may realistically need 24.875X2X2, or almost 100W per channel. So if you typically listen to average SPL of 75 dB like I do, you will only need only 10W at the most to cover the need of 20 dB of dynamic peaks, that is very rare in music contents. In that case you can get a 1000W amp and it should make no difference for you.
I set up an Excel spreadsheet that allows me to generate tables that saves time in doing such calculations, but you can Google the individual formula to do your own calculations for your specific situation.
I hope this helps.