Now the following questions pop up in my head.
Which amps are they ? (Whammy and Atom it seems)
Did you compare level matched ?
Did you compare them blind ?
Did you do enough comparisons (for statistical reference) ?
Which headphones ? modified HD58X
Is the output resistance of both amps known ? low enough in both cases.
'Attack' is in the 4-8kHz range and there is no amp that has difficulties with these frequencies.
You can measure squarewave response with the amp loaded with the headphones. Don't use more than 4Vtt as a test voltage.
Another test is to measure the current through the headphone. Connect a 10 Ohm between the headphone return (sleeve) and measure (scope/AP) the voltage across the 10 Ohm. make sure both drivers have signal.
Regarding the queste:
- See if a correlation can be found between objective measurements and subjective impressions.
Good luck with that.
1st: familiarize yourself with what you 'think' is the sound signature.
If you are really looking for accurate and meaningful results I suggest you build a switch that can switch the outputs of both amps to the HD58X.
Use a music source with a variable volume control. Set the volume control of both amps once so they have the exact same gain (output level) within 0.1dB. Also do not forget there are 2 channels. This means levels between L and R need to match within 0.1dB.
Good luck with that, you may need a pot in front of each amp to correct for L-R balance which varies on volpot position.
The you need to limit the 'tests' to later in the evening and spread over many days (take a month for this) and do the tests when you are comfortable and rested.
The most important part is the blind test part. You can NEVER know what amp is playing.
For this you need to involve someone else that sets the switch in a certain position and that person must keep a log.
You
must not be able to see the switch position !!!
That person must operate the switch when you are not present and needs to do this randomly every few days or so. It can remain in the same position for a week or several days in a row or switched the next day. NO pattern !
No switching when you are present !!!
All you need to do over a month or so is listen and make your notes what you think you hear. Possibly gamble (in your case know) what amp you think is used.
After a month or so compare your notes to that of the switch log and with enough statistical attempts (would say 20 attempts minimal) see how you scored and how accurate it was.
Then post your results here and not at SBAF (you will be regarded as 'deaf').
When you decide to test without such controls then post your results at SBAF and not at ASR (your results will be regarded as subjective non confirmed and worthless babble).
Succes.