I'm posting the reply to Wannabes comments here since it was posted erroneously under console bits.
Believe you me, that whilst the actual speaker is only small, it packs one hell of a punch right down to 16' and quite well to 32'. So much so that it is rare that one can turn the bass control up past zero without rattling the windows.
I have a set of Tannoy dual concentric 15" in 1m x 1m x 1/2m cabinets and they have nothing like the power of these beasts. Having adequately produced a decent sound in the main hall at Nottingham Uni with the Tannoys, I reckon the Logitechs would do equally well if not better.
I bought 6 sets for organ use on a two manual which totals 2400 watts !!! This is more than adequate for most buildings.
I also further boost the 32's with a couple of Roksan bass units which go right down to 17 Hz before roll off. and handle 300 watts apiece.
When all said and done, these Logitech speakers are selling at £60.00 a set and therefore my 2400 watt set up cost a mere £360.00 !!! which I think is pretty well unbeatable.