Hi-fi (6)
I believe the answer is:
stereo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hi-fi</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for stereo that I've seen before include "Sound transmission through two or more speakers" , "Musical sound with two speakers" , "One might play record" , "Music-playing equipment giving depth of sound" , "Two-channel sound" .)