Topic: RME ADI-2 DAC FS (AKM version) - turn on/off transient?
I've been measuring my ADI-2 DAC FS (AKM version) output stages (headphones TRS + XLR outs) yesterday just to find out the differences between the stock SMPS and an 12V LiFePo4 battery as power sources. As ADC, I used my RME Babyface Pro. To my surprise and definitely, as a testament to RME engineering, there's absolutely zero difference in noise spectrum / THD measurements. That's very good info and proves that stock SMPS is very good - you definitely don't need a battery.
But what I have found out instead, to my surprise, that either the headphones TRS socket or XLR outs emit a very small turn on/off transients which result in barely audible pops/clicks upon ADI startup/shutdown. I have first noticed with my headphones and now I notice it via my KH120s.
I don't remember these pops/clicks were there, but I may just have un-noticed them in the past.
So the obvious questions - "were" these turn on/off transients always there and is this the normal, stock operation of ADI-2 DAC FS or it definitely shouldn't be there?
(To be honest, I have overloaded the headphone output stage during the measurements several times with 1kHz sine wave, but according to the manual, this shouldn't cause any harm to it. It also wasn't a full scale 0dB sine either).
Thanks in advance for explanation.