[Freo-1]

You can always find good and bad examples of each.  Suggest you read up on why recording professionals go active.  The professionals have no tolerance for "entertaining" colorations that audiophiles seem to crave, they work to find the truth.  Frankly I'm amazed that active speakers like JBL 305's sound as good as they do based on size and cost. 

Getting back to efficiency versus size of amp.  I've found that low efficiency means poor dynamics, lots of distortion, ultimate sound pressure levels and high efficiency translates into all sorts of sonic anomalies.  In my experience 90 - 95 dB/w/m at 8 ohms is the ideal compromise at realistic pricing (assuming those are honest real world values). 


The grip an amp has on the speakers is more than just numbers on paper.  It's a matter of control.  Resolution of detail improves if you move from barely adequate to plenty of power and control can improve.  Thankfully we live in the age of class D where power is extremely cheap.

Again, this is overstating the effects of active speakers.  Whilst I agree they provide some advantages, they are not the nirvana some people hold them out to be.  I'll stand by the assertion that many of the best sounding speakers available are passive, and one needs to provide them with proper amplification to drive them. 


Case in point: Anyone who has listened to a higher powered Devialet system using the mono configuration driving a quality large floor standing set of speakers will attest that it is among the best sound available at any price point.  Further enhancement can be achieved if the speaker is supported by the Speaker Active Matching (SAM) application. 


Class D does provide good value for watts vs dollar.  Having said that, many of them just don't quite get the treble as well sounding as more traditional amps.  This is due to the inherent design issues with Class D.  Granted, they have come a long way, and will likely continue to get better.   

[SJ David]

The following is my understanding of speakers and power:

Every doubling of power gives 3 dB of added loudness.

If a pair of speakers are 84 dB efficient at 1 watt, and if the maximum I like to listen to music is 90 dB,  then 4 Watts should be enough power?....1 watt gives the 84 dB of the speaker, 2 watts gives 87 dB , 4 watts gives 90 dB.   

If however, as JLM states, I want to experience those peaks of say 110 dB , then to go from 90 dB to 110 dB means a difference of 20 dB.

If 4 watts gives 90 dB, then it goes....8 watts gives 93 dB,   16 watts 96 dB,  32 watts 99 dB,   64 watts 103 dB,  128 watts 106 dB,  256 watts gives 109 dB. 

Therefore, with my speakers, I need about 256 watts of power to experience those peaks properly?   

But then I also need to consider if the speakers can handle 110 dB peaks and 256 watt peaks. 

Am I anywhere in the ballpark with this thinking, or totally gone?

As good as your B&W speakers are they are the limiting factor in your calculations above. The 5 inch woofer would struggle with full spectrum-sustained sound levels beyond the mid 90's-dB range. Trying to push them harder will only heat up the voice coils and likely trigger some amount of thermal compression (build up of heat can reduce sensitivity of the woofer). 

Truth be told I think you are in a sweet spot with that amp and speaker combination. The amp has a stout power supply and I suspect it backs up those 60 watts with plenty of current reserve.

[FullRangeMan]

I would reframe the question, "Why do you need more power?"
One of the reasons is passive cross overs are horribly inefficient compared to active crossovers. Stop the madness.
Get active speakers and let the designer match the drivers, the crossover and the amp. Problem solved and in the long run you save $$$ on amps and speaker cables.

+1 I agree with the 1º paragraph, its know that xovers lower the drivers sensitivity and add cost among others probs.

On the 2º paragraph if one have a small/mid size room and dont listen in hi spl he can use a FR driver and give up big woffers, tsc tsc tweeters and a evil xover and even the cost of the expensive designer.