Sound Quality...iPad vs iTouch

I'd appreciate anyones thoughts on why the digital stream would be better out of an iPad vs an iTouch.

Hi Harry,

While I don't think that it is possible to predict which would be better, aside from experience (yours or others), it is certainly conceivable to me that there could be differences.

The likeliest reason would be differences in the amount of jitter (timing fluctuations) on the signal that is received by the DAC. A less likely but still conceivable reason would be differences in radiated RFI that could couple into the DAC or other parts of the system.

Also, I suppose it's possible that the codecs (coder-decoder programs) used in the two devices to decompress the audio data are not the same, resulting in differences in the bits that are output, but I have no particular knowledge of whether or not that may be the case.

A great many design-dependent factors in the iPod or iPad could affect the amount of jitter on the signal that is output from the dock, including electrical noise that will be generated by digital integrated circuits or other circuit devices, waveform distortion caused by impedance mismatches, rapid fluctuations in power consumption that will occur as processing requirements vary from instant to instant, etc. The amount of jitter resulting from causes such as those would depend on signal risetimes and falltimes at various circuit points, "crosstalk" between different circuit points, the mechanical layout of the circuits, and other similarly unpredictable factors.

The sonic effects resulting from the iPod vs. iPad differences can be expected to vary depending on the design of the dock, the jitter rejection capability of the DAC, and on what kind of interface is being used between the dock and the DAC (e.g., S/PDIF or AES/EBU).

Best regards,
-- Al

Much appreciated Al. Thanks

As mentioned, it's hard to do an a/b test when the source is Pandora Radio (GIGO). So far it seems the iPad is slightly better, more like dusk vs dawn than day vs night.

The iPad certainly looks more impressive than the iTouch sitting there on the dock but it also lights up a dark room big time, even with the brightness turned all the way down.

I sometimes use an iPad 2 with the Apple Camera Connection kit ($30) to directly output 24/96 AIFF and FLAC files to a small DAC and headphones when traveling. (Yes, it's actually 24-bit, and not the 16-bit feed that you get through the mic-out connection.)

While tinkering around at home, I connected the iPad to my den system (Bel Canto DAC3 via BC USB Link), and noted that SQ is excellent. I also streamed wi-fi signal from JRiver and PC server via JRemote, with very good results.

More to the point, when I shut down the server feed, I notice that the iPad continues to play on for as much as 30 seconds in some cases. One could speculate that the iPad might be using an unusually large buffer capacity to stabilize signal and this might also in part explain its quality of playback.

I use both the iTouch and iPad with a Cambridge Audio DacMgic Plus and companion digital iD-100 dock.

Sound could be slightly better with the Pad, but very hard to tell.

Just hit the power button for the whole screen to go black (just as if it was turned off) while keeping the sounds alive.

I also use both with the special Bluetooth gizmo designed to work with the DacMagic Plus. Slight loss of fidelity, but huge gain in convinience as you can hold the iPod or Pad directly in your hands sitting from pretty mucb anywhere in your house and control both source and volume level as everything is ''Bluetoothed' to your main rig. Very cool.