I, as many of you, use a computer much of the time as a source for my music and movies. Music is passed USB and Movies HDMI. No analog audio is taken from the computer.
Since the computer uses the typical noisy switching PS it tends to be electrically noisy. I feel that decent audio equipment is designed with power supplies that filter line noise out pretty effectively already but I would like some opinions from others regarding that thought.
I have considered using an isolation transformer to help in filtering line noise but I'm not sure it would really benefit the audio equipment when used for that purpose.
Thoughts/experience?
What is the noise you are talking about and how much?
Hum is usually an ground loop and nothing to do with the power supply, but it can be.
What sort of computer are you using?
For AV work you do need things to a pretty high standard. That is why I build my own.
You can get very high grade power supplies which is what I use.
This is the one I used.
I only output HDMI from it and it is dead quiet with excellent video and audio quality.
The tower computer in the rack to the right is the audio workstation and that has an external DAC. That is the blue unit. Since you are only outputting a digital signal you don't need an external DAC. The tower computer has no internal sound card.
I would look to see if you have ground loop issues, this is common especially if you have a hard wired Ethernet connection. Cable and phone companies are notorious foe bad installations as far as grounding is concerned.
If you are sure there are no ground loop issues, then upgrading the power supply would be the way to go.
By the way there is typically no significant line noise from the grid. However there is now in the home a lot of RF noise, from dimmers and LED bulbs which can be a problem, but an isolation transformer will not help that. Typically the house wiring acts as a radio transmitter and components inside the cases of your units pick it up. The reason being that equipment is full of semiconductor junctions that can rectify what the internal wiring of components pick up.
