Watts and speaker sound quality

Originally Posted by Khaos 

You're comparing apples to oranges in a sense.
Both speakers have different sonic qualities, regardless of watts. Pricing is never a great way to judge a speaker, it's all about your ears.
In answer to your question though, wattage does not = better sound. As long as you have clean power, and it's enough to drive it at adequate volumes, more watts become irrelevant.
To explain better, assume you have two amps, both of which deliver clean energy. If a speaker at the desired volume only requires 50watts, the extra 200 aren't even used. They are more for headroom (peaks) in case the volume of the source spikes and more power is required.
Amps can give you better sound, although subtle. For instance, I personally believe an Emotiva amp compared to a $15k amp will sound virtually the same. The emotiva already delivers perfect energy. However, it is safe to say that both amps will allow speakers to sound better than most built in AVR amps. Even if the Emotiva was only outputting 50watts and the built in amp was outputting 150watts, there is no doubt that the Emotiva would probably sound cleaner and clearer.
More watts allows you to drive your speakers louder without distorting. That's the most common reason for getting high power amps. HT requires loud volumes and therefore more watts. Otherwise the speakers would distort and possibly break. Which is why it's possible that the 50 watts powering the studios wasn't enough at the volume you were listening.
Quality>Quantity

Originally Posted by Bill Fitzmaurice 

None, other than the volume the amp is capable of driving the speakers to.

Originally Posted by Paraneer 

A lot comes down the efficiency of the speakers. The Synchrony One's are world class speakers, the top of PSB's line. They are also 4 Ohm speakers with sensitivity of 90 db making them more difficult to drive. This is probabaly why they were mated with the McIntosh. The Paradigms are far more efficent - 8 Ohms and 93 db sensitivity. They need less watts to acheive the same volume level as the PSB's. But this doesn't mean you need 250 watts for the Synchronys - they should perform very good at far less power. Provided its clean, high current power and the amp is not overdriven into clipping.
Were both speakers you heard at the same dealer? If so, why don't you re-listen to the Synchronys with the 50 watt amp. Providing the the amp is 4 Ohm stable and will not clip, this should be adequate to get the PSB's up there in an averaging listening room. If you still think the PSB sounds better, then you know it is this speaker you have a preference for. There are many higher end 4 ohm speakers being driven by 50 watt amps in folks homes all over the world. My speakers, Vienna Bach Grands are rated the same as the Synchrony's - 4 Ohm and 90 db. I drive them with 125 watts per channel and never have to push the volume control to achieve satisfying volume. This is only half the power of the McIntosh you auditioned. Good luck in your speaker search.