Sound Engineer Advice

[#1]

Sometimes the scattergun approach does not always solve the issue and if by chance it does, another one can be introduced... giving the same problem.

Reminded here of an old cartoon where a huge mainframe computer is being stripped down by boffin type engineers on ladders because if was not working at all... and over to the side was a cleaner with her mop and bucket looking down at the mains plug laying on the floor! 

[#2]

@Minivanman 

The one I saw the cleaner had pulled the plug out and was using the outlet to power her vacuum cleaner. In my younger days I had a mate who changed his car big end bearings because the oil light was coming on. He then changed the faulty oil pressure switch.

[#3]

I have spent months trying to pin point where the interference is coming from to no avail hence I'd though I better start asking for advice.

I'm thinking it's now the USB cable, how did I come to this conclusion?

Well with all the advise from you all and your suguestions I have tried all the various options suggested. (Some I haven't tried yet like power conditioner and the isolation add-on).

I have tried on both my PC which I built myself but quite old now (I'm greedy wanted 2 PC's. 1st for general use i.e music streaming and browsing the web etc. 2nd is Purley for gaming). The humming just followed which ever PC I tested with from different power outlets and different areas of my house.

I also have a HP G7 homesever (Yes getting more greedy, but I value my data).
When testing with that the humming is still there.

I tested with optical cable but I still needed the USB to power the DAC and the humming changed to a very low hissing which you can only hear if you place your ear next to the speaker which is way better than that anoying humming.

I think, but I could be wrong that the cheap USB that I'm using might not be able cope with power and data signal at the same time. I tried looking the the USB cable that came with the DAC to test but I appear to have lost it, that cable was very short that's why I purchased a longer 1m one from Amazon which i'm using right now. I do wish I checked using the supplied cable first (school boy error).

The supra cable (which they say shields power and data from each other) has been ordered and I ordered some of those ferrite beads as well.

They should arrive in the next few days so I will keep you all updated.

[#4]

The USB cable is the first thing I'd have tried having had a similar situation on my iMac. I have a pair of Creative iTreague 3330 and being the way I am I wasn't keen on the green end of the 3.5mm Jack lead spoiling the aesthetics of the rear of the Mac so I bought one of these, and what a disappointment it turned out to be. The noise the cable introduced was shocking and made it unusable at low volume, so that got returned and I went back to my 'ugly' green 3.5mm one.

[#5]

I did first try different USB cables but they were just always with basic value ones as I believed that they all did the same job but different brands. Never tried with a USB cable that is designed for DAC and audio.

I think now, maybe the cable quality does matter.

[#6]

Hi,

I received my cable today even though it was supposed to arrive next day but the was delayed due to the weather funny how my bills still arrived regular like clockwork. Anyways I will swap out the cables in the next few days hopefully no more annoying humming.