It’s super easy to me to tell the RME apart from my Marantz and other DACs
In fact it takes me only seconds or minute to see if I like something and pinpoint it.
a musician with 40+ years of playing
Yes the Marantz (HD-DAC1) has a discreet analog output section so that is very different right there.
I would love to be able to build a DAC and monitor the THD level in the output stage to see what effect it has on the overall sound.
Measurements of THD (THD+N) [Total Harmonic Distortion + noise] are only static measurements and can therefore never (!) explain the sound of amplifier circuits if certain listener-individual values are undercut - it is similar with IMD (Intermodulation Distortion).
In the audio field we unfortunately have this standard situation: at the request of marketing people as well as the "decades of trained needs of the majority of buyers".
Static measurements of THD or THD+N (plus noise):
- e.g. at 1 kHz (one single measurement, one frequency).
- e.g. in a range from 20 Hz to 20 kHz (a number of single measurements)
Very simple dynamic measurements of IMD
- Here only the distortions of one frequency pair (i.e. only 2 frequencies) are measured.
Test the audibility of THD / IMD yourself:
Take audio signals and adjust the volume for your headphones. Note the volume (in dB !) and then reduce the volume on the Marantz HD DAC1 / RME ADI-2 PRO:
-dB -> THD / IMD [%}
-50 -> 0,316
-51 -> 0,282
-52 -> 0,251
-53 -> 0,224
-54 -> 0,200
-55 -> 0,178
-56 -> 0,158
-57 -> 0,141
-58 -> 0,126
-59 -> 0,112
-60 -> 0,100
-61 -> 0,089
-62 -> 0,079
-63 -> 0,071
-64 -> 0,063
-65 -> 0,056
-66 -> 0,050
-67 -> 0,045
-68 -> 0,040
-69 -> 0,035
-70 -> 0,032
Here you can read what @MC (engineer and owner of companies like RME) writes about THD:
"Very high values (10.0k) cause around -60 dB distortion (0.1%). It is therefore also possible to use K2 and K3 separately and intentionally as an effect. This can be quite instructive - when one notices that no difference between 0.1% and 0.0001% distortion is audible."
User’s Guide ADI-2 DAC v3.1, page 28
The more complex the music is (organ / orchestra / ...), the more dynamic distortions have an effect: Instruments, vocals are covered by a fog / curtain.
To evaluate audio amplifiers we need other standard measurements:
- DIM (Dynamic Intermodulation distortion) in %.
- TIM (Transient Intermodulation) in %.
- Multitone measurements in %
- For digital signal sources (file): Digitise analogue output signals, save as a file and compare with the original.