Added on page 1 to clarify on my grading system:
TEST METHOD:
To rate a dongle, I run them through this playlist of songs:
https://deezer.page.link/Ts87DLAzFJ2thicq9
It is lengthy and various enough to cover all element of sounds. Critical listening sessions will continue all the way to the final songs in the list.
My fist cycle of critical listening always start with the use of Etymotic ER2XR, a canalphone that I regard as very natural sounding that does not emphasize any specific frequencies. Then 2/3 through the session I will usually switch to my Planar Magnetic Monolith M565c or Beyerdynamic DT990. With the first complete pass done, I will usually conduct a second pass after some break and run them through with my Shure KSE1500 and Etymotic ER4SR alternately and this will give me better perspective on the maximum capability of the dongle in question - KSE1500 and ER4SR being ultra resolving will reveal anything that can be revealed.
If the dongle impressed me enough I will do a third session where I will focus on A/B comparison with those that I have already rated - usually trying to compare between the ones that seems to share similar traits and I will try to discern what makes them different (this stage can be quite taxing and painful to do)
Contenders will need to pass driving test of the notorious Tin HiFi P1 Magnetic Planar IEM and Monolith M565c at listening volume level not exceeding 66/100. Being able to deliver desktop grade fidelity will secure them 5 stars rating. In general the rest will also be measured on their capability to drive these two monsters.
And lastly, I actually use the dongles regularly and casually as much as possible, running shuffled songs and observe how they behave, sometimes these random sessions prompted me to revise my impressions and I will reflect it on what I have wrote earlier.
