Complex sentence: A common modern view is that stereo isolation must be higher than this to achieve a proper stereo soundstage, however, in the 1950s the BBC determined in a series of tests that only 20--25 dB is required for the impression of full stereo separation.
Split into simpler sentences: A common modern view is that stereo isolation must be higher than this to achieve a proper stereo soundstage. However, in the 1950s the BBC determined in a series of tests that only 20--25 dB is required for the impression of full stereo separation.