Tone2 Pro - hybrid volume control

[khadas22022]

@Eric68

You can see the relationship from the table below.

	DAC Volume	Analog Volume(NJU72315)	Balanced RCA Output①	Single End RCA Output①	4.4 Headphone Output①	3.5 Headphone Output①
Low Gain	Fix to Maximum	Adjust from -12dB to -62dB	4Vrms	2Vrms	0-5Vrms	0-2.3Vrms
High Gain	Fix to Maximum	Adjust from 0dB to -62dB	4Vrms	2Vrms	0-2.5Vrms	0-1.15Vrms
Pre-AMP	Adjust from 0dB to -127dB	Fix to Maximum	0-4Vrms	0-2Vrms	0-5Vrms②	0-2.3Vrms②

①Note: The results are built on the condition that the digital volume is fixed to maximum and the audio signal souce is 0dB.
②Note: The headphones’ outputs are varying from the RCA outputs.

In summary,if you want to use headphone Jack,I suggest you to choose the low or high gain mode according to the impedance of the headphone.If you want to connect to power amplifiter or active speaker,and the volume of the speaker can not be easy to adjusted,you can choose Pre-Amp mode.

Hi @Eric68 - I saw this table in a different thread. This is very helpful! I wish it was in the user manual !

When you say “choose the low or high gain mode according to the impedance of the headphone”

What impedances is low gain for and what impedances is for high gain ?