October 2010 issue - Page 6 - Mac Mini

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Leigh Penny wrote to us asking whether he should use the optical or USB output of a Mac Mini. He wasn’t happy with Noel’s reply in our September 2010 issue – and nor were other readers! Here’s the saga...



I wrote to you with my situation (in the email below), of which I have just read your reply/comments, in the latest issue (September 2010). I don’t feel that you have commented correctly or given much relevant advice on the matter.

Firstly, you say that you are “not aware that Mac Mini’s have an optical audio output”. I think you’ll find most do, well at least for the last few years anyway. Its headphone jack doubles as one giving 24bit-192kHz. You would have to use an optical cable that has TOSLINK to MINIPLUG, i.e. “Van Den Hul Optocoupler MkII (Toslink to Miniplug).”

Then you advise I get a “Musical Fidelity V-DAC” even though I’ve asked for advice on DACs costing £1,000-£1,300.

I feel you have dismissed a lot of what I wrote. I would still very much appreciate any help or advice

Leigh Penny



New Mac Mini outputs digital audio from USB, optical jack and HDMI.


Optical vs. USB

Since the age of 15 (I’m only 25 now) I’ve read hi-fi mags and have come to favour your magazine over the others, based on auditioning a large variety of equipment over the years and tending to agree with a lot of your reviews. So I thought this to be a great opportunity to write in for your opinion on my current dilemma. Since my CD player died, I’ve been seriously researching the best way to incorporate a music server into my hi-fi system. Even though I build PCs and use Microsoft Windows on a daily basis, I’ve decided against this route in favour for an Apple Mac Mini.


The problem is that I can’t decide whether to go Optical or USB. My current system consists of: Dynaudio Audience 82 speakers (real wood version), Audio Note L3 preamp (that I built and upgraded with a remote controlled Dact stepped attenuator) and the original Quad IIs (that I’ve sympathetically modified). I know the Quads aren’t ideal to drive the Dyns but I love the sound they produce and I live in a flat, so the low power probably keeps my neighbours happy.

Ideally I’d like to build an AudioNote DAC to connect the Mac Mini to my system, but it doesn’t have an optical input. In my mind I’d prefer to use an optical connection to isolate noise from the Mac.

I have also read that the Mac doesn’t automatically switch between sample rates when outputting to a USB DAC. So I have to change settings in OS X to the correct sample rate of each track to ensure bit-perfect output. But I can’t find information on whether this is an issue when using the optical output.

Most of my music will be ripped from CD to WAV or AIFF format using error correction. But I will want to download higher sample rates in the future when they become more available and I know manually changing the sample rates on the MAC will become tedious. So the questions are: do I use Optical or USB? And if I were to use Optical, what DAC would you recommend for around £1,000-£1,300? Any help/advice would be much appreciated.

Leigh Penny



Maplin's NIKKAI cable and the important bit - an adaptor to fit a  headphone socket (right).



I read with interest the letter from Mr Leigh Penny in the September issue. The Mac Mini does indeed have an optical digital output and has a digital input too. I have never used this but regularly use the output via a Toslink cable connected to a Musical Fidelity V-DAC. Initially, I was puzzled by Apple’s claims that the computer had both a digital input and output (the computer manual is not helpful here) until a little research revealed that what was needed was a Toslink to mini Toslink adaptor. The jack sockets on the computer are dual purpose and when a Toslink cable fitted with the adaptor is used, they give a digital connection.

Like Mr Penny, I too would like to learn about the pros and cons of optical and USB connections and although I find the sound I am getting from computer is generally very good and musically satisfying, I am never sure if everything is set for optimum performance. As someone who became interested in hi-fi in the sixties, I feel at home with matters analogue and although I am familiar with computers and use them on a daily basis, I still feel a bit at sea in the world of computer audio.

I look forward to your magazine every month and always find it an interesting read.

Tom Mercer




Sampling rate options for USB were 44.1 and 48kHz with our Intel Mac Mini running Leopard, connected to a Cambridge Audio DAC Magic able to process 96kHz.


When it comes to computer audio, I have always regarded your magazine as sort of ‘charmingly misinformed'. But your response to the ‘Optical Mac?’ question however was at best, wrong. At worst it could be described deliberately misleading. Go to - for more information on the Mac optical connection.

Mr Penny asked a question about automatic sample rate switching in OSX. The response he got failed to answer the question and was on most individual points incorrect.

Mac Mini’s do have, and always have had, a digital output. Mr Penny is correct when he says that the audio resolution, of sample rate and bit depth, must be preset within Core Audio prior to playback by iTunes. This is set in ‘Audio Midi’ settings. If this is set incorrectly the audio stream will be sample rate converted to match the setting. So, if Core Audio is set to 16/44.1 and Mr Penny plays a 24/96 file, the file will be converted to 16/44.1 prior to being sent to the DAC. There is no automatic way for the sample rate to be matched ‘on the fly’ without investing in additional software and/or hardware.

Mr Penny’s question was to whether this sample rate matching issue was applicable to the optical output. The answer is yes, it is. The issue is one applicable to OSX and will affect all outputs.

I can fully understand that ‘computer audio’, as a whole world if you will, is not the main emphasis of your magazine and that’s fine. Even the slightly patronising tone that is often used, when it comes to things ‘computer’, is okay. The world of audio playback is nothing if not contentious! But incorrect information is unforgivable. You owe Mr Penny an apology.

Bob Hurst



In response to Leigh Penny (HFW 20(7) p43) Noel Keywood states that the Mac Mini lacks an optical output. The optical out on a Mac Mini (and the Macbooks and Airport Express) is integrated into the 3.5mm audio out connector and will happily talk to a conventional Toslink socket with the appropriate adaptor plug. Sample rates and bit depth can be tweaked via the Audio Midi application; any additional USB audio devices will show up here too. I’m not sure if all iterations of the Mac Mini have had the optical out so integrated, but I'm fairly sure that all of the Intel based Mac Minis have. Hope this helps. Certainly my three year old MacBook has one as well as my newer machine.

Dr J.D. Atkinson


Your statement that Mac Minis do not have an optical output is not correct, as a quick check of the spec sheet on Apple’s website would have shown. The 3.5mm mini-jack on the machine is, in fact, a dual-purpose analogue stereo and mini Toslink output. It is the same interface used on the Airport Express wireless base station and in Apple laptops.

USB may well be a better bet however as the Toslink connection won’t pass sample rates higher than 24 bit/96kHz. FireWire is also a possibility for digital output, as is HDMI on the latest model.

Collin Coleman




A USB device declares its identity and must be selected in the Sound control panel within System Preferences.


Oh dear oh dear. NK is simply mistaken to claim that the Mac Mini does not have an optical output in the Letters column of Sept ‘10, when replying to Leigh Penny. The headphone socket on the back is a combination socket that also includes optical out.

Then there’s the subject of bit rates, etc. On my Mac Mini using OSX 10.6.4 (and indeed earlier versions) once there is an optical output lead connected to an external DAC, you can alter all sorts of parameters in Utilities > midi > sound input/sound output. I’ve been using my Mac Mini via optical through a DAC for about three years, and I believe (and this personal) that the optical is superior to the USB, to me it just sounds better.

Steve Dixon



Well, I never knew that! My thanks to all our readers who obviously have Mac Minis and know more about them than me – and even Apple (more later)! And my sincere apologies to all for an inadequate answer.

I bought one of the first Mac Minis and have been using it at home as a ‘silent’ companion ever since, keeping it up to speed with regular DIY disk drive and memory upgrades. So I thought I knew it – and I do. It has no optical output in the headphone socket. Later Macs do, including an Intel Mac Mini I also have (but do not like because the interpretation layer makes it slow), so whilst strictly 'not wrong', I wasn’t usefully right either!

Suitably chastened by your letters I trotted down to Apple’s Mac emporium on London’s Regent Street and asked for an adaptor. “A what?” was the reply from three assistants (I got passed along). After thirty minutes in the stock room a Mac expert sold me a cable that, he assured me, had the adaptor in the box. You can guess the rest. I got the darn thing at Maplin in the end, as an accessory packed with an Nikkai optical cable. So if you want one, try Maplins!

I admit I have never thought of my little, unpretentious and silent companion as having any audio leanings, other than to deliver music from YouTube late at night, when my fingers have reached meltdown. But there’s plenty on the ‘net about Mac Minis being used like this.

Why wouldn’t a Mac Mini deliver music properly? For the usual quoted reasons; noise and jitter. Intrigued by the notion of using a Mac Mini for music (I’ve always associated music and video with my PC) but suspicious that this isn’t the best of ideas, I connected up the Intel Mini’s optical S/PDIF line to our Rohde & Schwarz jitter analyser and saw very little jitter at 44.1kHz sample rate. It looked good. Switching to 48kHz sample rate, jitter and noise rose considerably, suggesting the Mac Mini isn’t ideal. Unfortunately, our analyser doesn’t measure jitter on a 96kHz signal. So it looks like a fair choice of music server, but it’s by no means perfect and hardly purposed for this role. Note that using Optical does not isolate this type of noise. And look at what Naim say about this on their website with regard to the Naim DAC, certified to work with Macs and designed to suppress computer crud.

The Intel Mac Mini has selectable fixed output sample rates of 44.1, 48 and 96kHz via the optical output but only 44.1 and 48kHz via USB, at least with a 96kHz capable Cambridge Audio DAC Magic attached as a test mule, and running OSX Leopard 10.5.8. This may well have risen to 96k in the new Mac Minis, running Snow Leopard, with which I have no experience. It sample rate converted 44.1, 48 and 96k WAV sample rate test files up or down successfully too, meaning 44.1 up to 96k (which is not a multiple) and 96k down to 44.1, without obvious problems. I did not spend to much time on this but the spectrums were clean. Sample rate conversion to non multiples/submultiples can have problems.


The 'Format' set is the Mini's output data rate, irrespective of the music file rate. A data rate of 96kHz, shown here is the maximum. 'Digital out' means optical S/PDIF.


As readers have pointed out, output rate is set in the Audio tab of the ‘Audio MIDI Setup’ device, found in the Utilities folder, within Applications. Once set, this is the output rate; you do not have to change it. All files are converted to this rate.

Subjectively, optical connection is usually preferred to electrical, if not by everyone. Optical introduces an extra transmitter and receiver which I am told “can have problems”. But there is no signal ground return path to be shared with earth currents and this is the usual quoted advantage, lessening ‘noise’. Optical coupling of S/PDIF invariably gives a less sharp sound than electrical, or one with less temporal definition, according to how you see it. HDMI and USB have the same character as electrical connection, optical having a quite distinct flavour.

All in all then, I suggest you use optical; I usually do. It is a relaxing yet clean listen. The Musical Fidelity V-Dac I recommended is a suitable budget match but a Cyrus DAC-X at £1,200 would be a quality partner. AudioNote’s DAC is quite different in its anti-alias filtering to all others and uses valves of course. You could use a USB-to-S/PDIF converter,  assuming 96k is available from USB in the latest Mac Minis. There’s plenty of music around in 24/96 and it worth having; 24bit resolution especially. I would not worry unduly about 24/192. There’s so little music around at this resolution and my experience to date is that there are no night-and-day advantages over 24/96; generally, it has more intense detailing. And the Mac Mini does not support it yet as far as I am aware, although HDMI on the new Mini has the bandwidth.

I hope this makes all the issues clear – and makes everyone happy too! And my apologies once again for the wonky reply. NK



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