Very nice photos! As a pro EE though, just wanted to correct a few misconceptions in step 6:
Flux: if they used the right type of flux, leaving it on is fine. Many switches and potentiometers can’t be “washed” because they’re not sealed (the liquid would get stuck inside), so after SMT assembly and cleaning, these are usually hand-soldered separately using “no-clean” flux - this class of fluxes is non-corrosive and safe to leave on the board permanently. The only reasons to clean flux off the board are DC leakage currents (which only matter for pA or fA measurements, nothing in the audio realm will matter at all in this way) or corrosion (if you’re not using a no-clean flux).
Resistor values: definitely no gigaohm values; leakage around the resistors is probably in the gigaohm range. These are using the EIA-96 style resistor codes, which are standard on 0603 and smaller - I can see how it would be easy to misread the “B”s as “8”s. The schematic for each channel looks something like this.
Sobald er das hat, wird er in der Lage sein, eine Grafik zu seiner im Laufe der Zeit erlangten Reputation zu sehen.
Hier ist eine Vorschau, wie die Grafik aussehen wird:
Noch keine Reputation erlangt.