plastic penguin said:
Really depends how the speakers are mounted (dedicated stands, brackets or table...). If stands, and given a little breathing space, look for a s/hand pair of PMC DB1i or + versions. They are quite efficient (87db into 8 ohms), and you can pick up a good pair for between £500-600.
Are they?
I may be wrong but my guess is that they are at best about 84db/m/w sensitive despite what PMC are quoting. This would be more in line for what I'd expect of a speaker of this size. The previous quoted Harbeth is probably even less.
Still, I am not familiar with the Sonos amplifier but if high volume is not required (and why would you buy any of the above speakers if it was) this may not be a problem if the PMC or Harbeth are a relatively easy electrical load.
I'd happily (!) have the Harbeth and forgoe a little outright volume.