Hello, Recently I decided to upgrade my stereo system and I went for this config: 1. Took the sound out of my PC through USB to a Creative Omni 5.1 sound card running in stereo mode. 2. Picked up a Onkyo TX 8270 amp and hooked a pair of Dynavoice Challenger M105 EX V4. 3. The link between Omni 5.1 and amp is done via RCA analogs. I wanted this because I plan to use Zone 2 in the future and Onkyo's Zone 2 is only analogic. But I have an issue. If the system does not play any sound and I crank up the volume from the amp, I can hear some background noise coming from the speakers. It's in the treble domain (high frequency). So I assumed first that maybe my speakers\amp are broken somehow and I did some tests. If I stream the music from NET source (Tidal for example), than put the system on pause and crank up the volume there is NO background noise at all. The same is valid if I use a toslink\optical connection of the same Omni 5.1. With these, it is dead silent, so the speakers/amp are not broken. So the noise seems to come from the Omni 5.1 analog outputs. The digital part of the Omni 5.1 is fine, but analogs seem to put out some noise. I went further and I removed the Omni from config and I took the sound out of my PC directly from my sound card to my 8270 amp analogical only through a 3.5mm headphone connection. The noise is still there, but the level is far smaller than with Omni 5.1 analogical. How can that be? Creative Omni 5.1 is a 2017 model and advertised as a high quality sound card while my motherboard sound card is 8 years old. Is it possible that DAC in Omni is of poorer quality than my PC? And one last question: can I get rid of the noise if I place a DAC between digital Omni 5.1 optical out and my Onkyo TX 8270 amp? I was thinking to get a Cambridge Audio DAC Magic 100 for this purpose but I am not sure that will 100% help me. I need to preserve my analog input to the amp for Zone 2 compatibility.