Over on the Headphonic forums someone asked me to give them a bit of a run-down on how capable a PA2V2 is for driving Beyerdynamic DT880s. Although the PA2 performed quite well with the Ultimate Ears SuperFi3 canalphones, the DT880s are notoriously hard to drive (at least according to most of the headphone-centric websites around the place) so I was expecting the little amp to struggle a bit.
I initially planned a 3-way test, driving the DT880s from
- the headphone socket of a 5th Gen iPod video
- a PA2V2 using line out from the iPod, and
- an O1 amp using line out from the iPod
Out of 7 tests I picked 6 correctly, so there was a noticable difference. Interestingly though, the difference was nowhere near as apparent as I had expected. Although the iPod was struggling to drive the DT880s to a decent volume (tests were done with the iPod at around 80% volume) the sound itself was not overly different between the two. The PA2 had slightly better instrument separation and clarity and the ipod seemed to mildly over-emphasise the mids.
I wasn't that shocked though - the PA2 is afterall a small, cheap, portable amp. With the DT880s repution maybe it just wasn't up to the task.
Next up it was the PA2 vs my newly aquired O1. Being a desktop amp that's fairly well regarded, I figured that the O1 should be fairly capable of handling the DT880s demands. This is where the surprise really kicked in. Although again I picked 6/7 correctly, the difference was even smaller than the first test. The O1 had slightly better detail and 'weight' but you had to listen for it. I was expecting (as when I tested the PA2 with SF3s) the difference to be instantly obvious.
At this stage I decided to expand the tests to include a better source. Surely this was just the iPod's DAC being the limiting factor? So I switched to a mid-level Panasonic DVD player, using a couple of RCA splitters to run the signal to both amps. The results? Exactly the same. The two amps were almost indistinguishable. This was now getting a little disturbing, as I've been sure from subjective listening with MS Pros over the last few weeks that the O1 has been a great improvement.
Maybe it was the O1's DAC that was making all the difference? So I hooked up the DVD player's analog out to the PA2 and coax out to the O1. Now we're in for a show.... or not. Again, there was very little difference, to my ears no more than with both amps running off the split analog signal.
What can I conclude from all of this? I'm completely baffled by the results, especially when the much easier to drive UE SF3 showed a much greater improvement with the PA2. One possible explanation is that all the amps I tried aren't up to the task of driving the DT880s, and as a result they were all similarly unspectacular. At the other end of the possibility spectrum I could conclude that amps make little or no difference to sound quality
A while back I spent ~$600 on a Talisman T-31H to drive the DT880s and was similarly underwhelemed by the lack of improvement over my NAD stereo amp's headphone socket. This, combined with having heard significant differences from amps in the past, makes me anecdotally lean towards the theory that the 880s are just particularly fussy. Unless I get my hands on a much higher quality amp that the T-31H though I have no way of verifying that.
This experiment has reaffirmed my belief that without doing A/B testing it's really, really easy to fool yourself into hearing significant differences in gear that may not exist. This opens the door for a whole lot more testing, in particular comparing the O1 and PA2 using the MS Pros and SF3s.
To answer the orginal question I was asked: the PA2V2 is an improvement over an iPod with DT880s, but it's only marginal. It may be worth the money simply to extend the iPod's battery life and give you more volume if required. My suspicion is that you would need to spend a lot more on an amp in order to start seeing appreciable differences over the PA2, so if you can live with the ergonomics of a portable amp it may be quite a good option.