iPod headphone socket vs line out + PA2V2 amp

A little while ago my main amp - a NAD 3150 integrated - developed a problem in the pre-amp stage which has meant that I've been using a PA2V2 portable amp in my main setup. As timing would have it, the PA2V2 never actually made it to work, which is what I bought it for. 

With the immenent arrival of my new headphone amp and DAC, the PA2 will be free to head to work. Before it does I wanted to do some quick tests to see if it actually improves sound quality at all.

The testing setup was pretty simple:

  • 60Gb iPod video in a standard Apple dock, playing 320kbs CBR mp3s (lame --preset-insane)
  • A/B switch box connected to the iPod's headphone jack
  • PA2V2 connected to the line out of the dock
  • A/B switch connected to the PA2V2
  • Ultimate Ears SuperFi3 canalphones
After level matching the volume by ear using a 400hz sine wave I started as I usually do: fully sighted subjective listening. It was immediately obvious that a simulated blind test wasn't going to be needed - there was a very significant, easily detectable difference in the sound.

The first stand-out difference was in the quality and amount of bass. Initially I thought it may have been the amp adding some mid-bass EQ (which it may do) but the sound didn't become muddy as is usual with in that case. In fact throughout the specturm instrument separation seemed to improve, and the soundstage widened appreciably. 

Best of all, the sound was much more dynamic and lively with the PA2V2. By comparison, the headphone socket sounded flat and dull. Given how little power the SuperFi3s require (I often listen to them on the ipod's lowest volume setting at work) I was really surprised at the difference even a cheap amp like the PA2V2 made.

Is it enough of a difference for me to carry a LOD and amp for portable use? Nope - it's just not worth the fuss to me. However it's definitely worth the price of an iPod dock for work.

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