actually I'm not using dangerous listening levels - really carefully read the Headwize "Preventing Hearing Damage When Listening With Headphones" article
http://headwize.com/articles/hearing_art.htm
the average level I was using as an example was ~ 90 dB - perhaps I should have said "more than comfortably loud" - but way less than live club levels and quite safe at the hour or so I might devote to a critical listening session - not as background music
the +100 dB peaks were <10% of the set’s running time as the brass punched out the theme, the percussion must have been pushing the instantaneous peaks ( for only milliseconds ) 10dB higher
the OSHA exposure limits allow 90 dB for 8 hr/day, 2 hr for 100 dB
Osha isn't the final word on hearing safety but I'm staying at least 4x below their daily exposure time limit for any level - and not freeing up the time for a critical listening session every day
I would be very critical of the amp/headphone mismatch if I tried to listen with 600 Ohm DT880 paired with the SuperMacro IV LE
It isn't obvious from the published info I've found if there really are meaningful differences in the DT880 sound with different Z coils - when driven with amps that have the appropriate range of I,V output for the load Z
the idealized view of coil Z is that of a transformer - changing the turns ratio while using the same weight of conductor doesn't change the transducer response - only the relation of I,V at the terminals
it isn't clear from the Beyer site if they are doing this and we're just seeing some marketing copy writer's misstatement, or if they are really changing electro-acoustic design by changing voice coil mass - frequency response and impedance graphs would be helpful
but giving weight to head-fi discussions on the issue seems a little naive
1st of all I dismiss any anecdotal commentary by anyone who doesn't have both versions in their hand - no "I heard it at the meet last month..."
and it would be awkward but it is absolutely necessary to Measure and Match spl levels before any listening comparison can be considered reliable - the same system at different loudness levels is perceived to have different frequency balance - see the Fletcher-Munson curves
Then I would like to see the production distribution of driver detailed frequency response - it is likely that even serial production cans have discernable small variations in their frequency response that would allow individual headphones to be distinguished by high resolving listening tests - which makes answering the question of whether any reported differences between differing Z versions is truly attributable to the Z difference more difficult
and of course good amplification shouldn't add anything to the sound but it is likely that many tube amps do change the sound and 600 Ohm cans are much more likely to found on tube amp setups - adding again to the uncontrolled variables that could be expected to interfere with even skilled, but individual, uncontrolled (in the scientific sense of not having a reproducible reference) anecdotal commentary on the headphone's sound
"The numbers" can't tell you what will sound good but the very basics of how loud can this amplifier get with this headphone without clipping (and how loud it needs to get to reproduce music) shouldn't be dismissed/ignored if you really want to get serious about the more subtle issues everyone here seems to feel so important
