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Posts by stv014

 The differences might be there, but if only 30% of your guesses were correct, then from that it does not look like you can actually hear them. Choosing randomly you would guess 50% right on average. With 10 trials, a score of 8/10 means there is 5.5% chance that it was only by luck, and 9/10 reduces that to 1.1%. A commonly accepted threshold for "passing" the test is less than 5% chance of random guessing, and that is with a single run of a pre-determined number of trials.
 Even a cheap multimeter can be adequate as long as it can measure AC voltage with any reasonable accuracy. It does not need to show accurate absolute levels, since it will only be used for the purpose of testing if two voltages are equal. You will also need a splitter to be able to measure the output voltage of the amplifier while it is driving the headphones. This is not required if you know for sure that the output impedance of both amplifiers is at least 100 times...
 Even if your figure of 0.2 dB is correct (which is doubtful, especially if the matching is done sighted, with music, and without the ability to switch in a fraction of a second between the amplifiers, it is not so easy to decide for sure when they sound the same; not sure where you got that number from), it is actually not good enough. There have been reports of people successfully detecting that difference in ABX tests, for example on Hydrogenaudio. Now it may be argued...
 It should not sound different for the higher maximum power output alone, as long as the following conditions are met:- you listen to the amplifiers at accurately matched levels (this requires measurements, preferably of the voltage on the headphone drivers while playing a tone at a constant level)- the lower powered amplifier never clips or has otherwise excessively high distortion at that output level driving your headphonesOne common reason why people often find higher...
 I was not referring to THD measurements, but rather noise and dynamic range. It can be tested easily by using the "Generate WAV" function of RMAA in 44.1 kHz/24-bit format, then adding noise to the WAV file (for example by reducing its effective resolution to 16 bits with TPDF dither using this utility), and analyzing the modified WAV with RMAA. Other measurements, such as crosstalk, can be tested with the same generate->process->analyze method. In the case of the...
 That is, unless it is a worse master than the (older and in some cases dynamically less compressed) 16 bit version.
 This problem has already been discovered a while ago, and is mentioned for example in this older post. Apparently, they still did not fix the bug after 2.5 years then. There are (or were, if already fixed, I have not used RMAA recently) also issues with how the A-weighted noise level is calculated, again making the measured device look a couple dB better than it really is.
 The foobar volume control is digital, and most likely the Windows one too (unless the device supports digitally controlled analog volume, and it is exposed to the OS/applications via a driver, which I doubt). In theory, digital volume control reduces the sound quality by lowering the dynamic range, but in practice this should only have an audible effect in rather sub-optimal cases, such as very low digital volume combined with high analog volume and gain. Obviously, if...
If one has a DSD capable DAC, ABX software that is capable of playing DSD files (if I recall correctly, there is a foobar2000 plugin for that ?), and software for converting PCM to DSD, then it should be possible to compare unmodified DSD to a DSD->Red Book->DSD conversion. But if ultrasonics are so important, then converting the DSD to 176.4 or 192 kHz PCM (which can be played by most hardware) first and using that as the reference should not be a major issue, because if...
 That depends on exactly how the AC hum is added to the signal. Maybe it is affected by the impedance of the load, or in the loopback case the physical placement of the cable was different. Also, was the loopback recording done in exactly the same configuration (same DAC, same amplifier, same cable, and same ADC) as the test with the driver ? Perhaps it would be of some help if you posted actual recorded samples in all configurations that might be worth testing. You can...
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