This is probably the 20th question I'm answering about R6 2020 + Andromeda's hissing today. Haha. Andromeda is like everyones favourite litmus test. Lol!
Andromeda hissing from SE in Low Gain is so faint that you got to focus hard to hear it. 5 songs into my playlist at good volume and my ear ringing is much louder than the hissing. That's how low it is. Lol! Jokes aside, I can only hear it VERY faintly for a second or so when the I pause the song before the DAC goes on standby or in the rare song where only one instrument is playing (not all songs). I definitely don't hear it in busy sections of songs. In most songs, I perceive a nice black background with Andromeda plugged into SE too. Hissing is slightly more prominent through 4.4mm BAL in Andromeda but I personally don't use the balanced outputs for sensitive IEMs. I perceive almost no hissing in SE with Fibae7 (5.9Ω) or Craft Ears Four (10Ω), both low impedance and fairly sensitive multi-BA IEMs.
If you want me to test a specific song for you, let me know. Cheers!