What I discovered testing 5 Apple TVs with the DAC-V1
Posted by: GregW on 04 September 2014
One of the things I love about the NAP 100 / DAC-V1 is way it makes digital sources come to life: I would even go as far as to say it can sound very analog with the right material, especially over USB. However, I been using an Apple TV with my DAC-V1 recently and found the sound somewhat lifeless, a little dull and in some cases downright odd.
I double checked with Naim to see if the DAC-V1 is actively managing jitter on Toslink connections. It is which is a great because poor jitter control is not at all uncommon with low end transports like the Apple TV.
From the NDX white paper. The DAC-V1 uses the same circuit. "Naim’s buffer or memory method of jitter removal relies on a simple concept: the audio data is clocked into the memory at the incoming, inconsistently timed rate and is then clocked out of the memory and into the DAC chips using a precise clock. The rate at which the memory fills and empties is controlled by selecting the master clock that best matches the average incoming clock frequency. In this way the data entering the DAC chips is completely isolated from the incoming jitter."
Based on my positive experience of the NAP 100 / DAC-V1 I decided to take a closer look at the Apple TV. My reference is an SSD based Mac Mini used exclusively, and optimised for music playback using Audirvana Plus. It's connected to the DAC-V1 by a Wireworld ultraviolet 1m USB cable. I use a 1m Optichord Toslink cable for the Apple TV.
So I grabbed 3 Apple TVs from the office and 2 from home. My wife swapped them in and out for me so I didn't know which unit was connected. After spending some time carefully listening to them, I concluded 2 sounded lifeless and not at all enjoyable to listen to. This included the one I originally had connected to my DAC-V1. 3 sounded quite reasonable, but there were still differences. Night and day would be an exaggeration but unlike the other 2 they didn't get in the way of my musical enjoyment, in fact they sounded pretty good.
The good news is that the DAC-V1 can help a fairly average transport still sound musical and enjoyable. The bad news is that there would appear to be noticeable sample variability with Apple TVs. Unfortunately the 2 lifeless sounding Apple TVs, were a 2nd and 3rd generation unit so I can't narrow it down to one particular generation in my n=5 sample.
I'm hanging on to the 2 best units at home and taking the naff units back to the office! They are only used in meeting rooms so audio output quality is not important.