Electret Preamp Shootout: Superlux PS 418S vs DIY Kaiser vs the t.bone CC100RC Stock vs Mod

I use a Beyer Dynamic TG H54c tan Headset.
The t.bone CC100RC Stock distorts quite quickly, changed the zener diode and now it is usable.
0:00 Superlux PS-418S
0:20 DIY-Kaiser
0:40 the t.bone CC100RC Stock
0:59 the t.bone CC100RC modified
1:20 the modification