For nearly 30 years I worked as a sound engineer at the BBC and for many years ran a BM6000 quadraphonic amp driving 4 Tannoy Cheviot speakers (12inch dual concentric units in enclosures slightly smaller than the Lancasters). It was without dought the most wonderful sound you can imagine, slightly mellow, but full of detail especially in the higher frequencies. The BM6000 was later replaced with the BM7000 with similar results, although in a stereo only configuration, untill eventually the whole system was replaced with a Beosound 4 with BS3 and BS2 combination. The 4 Tannoys now sit in my garage waiting for the day that I can return them to the rightfull place in my listening room, having given them new foam surrounds (yes, other loudspeakers do suffer the same foam rot as B&O speakers!!)