Two different approaches to use ADI-2 with external amps, how to set them up:
CASE 1, analog volume control:
To maximize ADI-2's dynamic range (S/N ratio) it's best to have ADI-2’s volume control at 0 dB, using the external ANALOG AMP’s volume control to set listening level:
• Set external amp's volume control to middle position or some above.
• Switch OFF ADI-2's "Auto Reference Level".
• Set ADI-2's volume control to 0 dB.
• Select the reference level that fits best to your loudness demands.
• Use the ext. amp's volume dial to control the final loudness.
• Once you start to use any of ADI-2's DSP functions like e.g. the EQ, compensate possible level boosts with ADI-2's volume control until the Level Meter does not show overs.
CASE 2, digital volume control:
If you want to use ADI-2's digital volume control to set listening level, ADI-2 DAC / (Pro) has a clever option that increases the usable dynamic range by 18 / (20) dB: "Auto Reference Level":
• Switch ON ADI-2's "Auto Reference Level".
• Set ADI-2 DAC's (Pro's) volume control to -18 / (-20) dBr. (1)
• Set ext. amp's volume control (or passive attenuators) slightly above your normal listening level.
• Use ADI-2's volume control to set the final listening level.
Now ADI-2 automatically adapts the reference level for best fit to your loudness demands, while maximizing it's DAC's dynamic range.
If your external amp does not have a volume control, use variable passive attenuators to fit the level:
https://forum.rme-audio.de/viewtopic.ph … 42#p120442
The volume figures change from dB to dBr when Auto Reference Level is “ON”.
The dBr relates to maximum achievable level with highest Reference Level then.
With “Auto Reference Level “OFF” the dB-figures (without r) relate to the manually choosing reference level.