Improving music on a Mac

I play a lot of music through my mid-2010 27-inch iMac, but the sound quality isn’t as good as I would like it to be. I have a set of Harman Kardon three-way speakers but sound output is quite flat, with no real treble. I have experimented with iTunes’ equaliser to no avail. Could it be a mediocre on-board sound card, or should I look for a 3rd-party equaliser? Dave Morris Music quality – like the difference between a £6.99 bottle of wine and a £40 bottle – is something that most of us never appreciate and an unlucky few are haunted by. Before we decide which camp you belong to, let’s start with the obvious. Try listening through a decent set of headphones to rule out a problem with the speakers. If this makes no difference, open the Audio MIDI Setup app and ensure your Mac is outputting sound at 48kHz with 24-bit sampling. A corrupted preference file could have forced it into 16-bit mode, which a keen ear might hear. Try the audio test at bit.ly/1yGGwlu to see if the anti-aliasing filter on the sound card is responsible. If your ears are just too good for the iMac’s sound card, try an external one, such as the rPAC (www.arcam.co.uk).