As per my previous post my system comprised of NUC ROCK → ROON Ready Auralic Mini → RCA to AMP. I noticed hum and crackle noise when system is idle (cannot confirm they are still there when sound is playing).
Since then i replaced the Auralic for a Topping D30 Pro and connected my system now as NUC ROCK → USB to Topping DAC → RCA to AMP. Unfortunately i still have the hum and crackle noises (not always to make it even weirder) but also the volume level is way lower than my other sources. The CD player and my TV (via Toslink), both directly hooked up to the AMP, play nice on -20dB, the ROCK source needs to be a 0dB to reach same level of sound.
So 2 problems, where does the noise come from? Why is the input volume so ‘low’?
To get a better idea i switched my TV with toslink to the DAC instead of directly into my AMP and experienced neither issues. No noises and volume level was equal to other sources on my AMP.
So the RCA from the Topping to the AMP and the AMP itself are not a part of the problem, but the USB connected NUC with ROCK is. The Topping came with a cable and i read on all serious forums this cable should suffice, quality-wise.
Any ideas? I heard something about groundloops. My AMP is not grounded. The NUC and DAC are.