There always seems to have been a B&O sound - good bass and detailed but possibly slightly softer treble that makes the sound very easy to listen to for extended periods. This can sometimes be characterised as veiled by Hi-Fi magazines. The newer ALT speakers do not have this!
Within the range, there has always seemed to have been an audio range , which is lower priced and offers better value, and a hi-fi range which offers better performance.
Examples would be the Beomaster 901, which was audio range and the Beomaster 3000-2 , which was hi-fi.