iTunes sound quality rant

I don't use my headphones very often. They're ancient but very good. I've been working at night on a client site with a flat above and I didn't want to disturb the residents.

I was playing music using the iTunes player on my Macbook Pro. I use a Teac HA-P50 DAC conected with an optical cable as my headphones are impossible for the Macbook to drive effectively (they have a 600ohm impedance).

I was getting audible distortion on most pieces I was playing. They were from CDs I'd ripped using iTunes lossless conversion.

After a lot of playing around, I swapped the optical connection and fed the DAC using a USB output. This improved things noticeably but I was still getting distortion.

I thought it might be my headphones finally dying, as they're neary thirty years old, but turning the volume down really low, the distortion was still audible in exactly the same bits of music.

I then tried new source material and bought a 24bit 48kHz FLAC remastered version of one of the CDs I already had. I couldn't play this with iTunes so I downloaded TEAC's high resolution audio player app. The disortion completely vanished. Not a hint of it. I then played the standard CD tracks which had caused problems earlier, and they had no distortion either.

It's the iTunes app itself (12.3.3.17 - the latest version on El Capitan) that actually causes the distortion.

Grrr!

In reply to a post by caffn8me:

It's the iTunes app itself (12.3.3.17 - the latest version on El Capitan) that actually causes the distortion.

The version on my MacBook, also running El Capitan, is 12.6.1.25.


eta- the same as on the lMac with Sierra.

Edited by billford (Tue 18-Jul-17 07:16:29)

Thank you for that. When I try to update it, it tells me there isn't a newer one available. Having said that, I'm now downloading a new version from Apple's website. I'll let you know what happens.

Having just upgraded to 12.6.1.27, I can confirm that the distortion is still there. At least I don't have a large collection of iTunes purchased music. I only have one track that isn't available anywhere else. And, yes, it distorts

Interesting... and annoying for you

I've never noticed anything like that here, but I don't use lossless compression- mp3/4 or AAC. At my age, my ears wouldn't notice the difference

Might be worth transcoding a file to AAC to see what happens?

You haven't got the iTunes EQ on by any chance, with some boosted frequencies, and an overall positive gain on the EQ's master output signal?

Just speculating.

Edited by mixt (Tue 18-Jul-17 14:15:48)

Found this, may or may not be relevant depending on the CDs you've ripped.

Edited by billford (Tue 18-Jul-17 17:11:21)

No, all sound tweaking options are set to off - after enabling them first to check that they did actually turn on and off. Still no improvement.

I'm playing the exact same ripped files via iTunes and the TEAC HR audio player app. I've also used Audacity and they're as clean as a whistle - unless I play them with iTunes. If I get sufficiently irked, which I probably will, I'll get my test set out and measure THD for the different apps.

I'm on Version 12.6.2.20 on my iMac, and have all sorts, brought from iTunes, ripped from CD's, etc .... All with no distortion issues what so ever. Weird.