Keces 151 DAC > Woo3+: Radio Noise??

[IctusBrucks]

Hello,

I currently have this setup:

PC > Keces 151 > WA3+ > DT990

The 151 and WA3+ sound good, but when I turn the volume all the way up on the WA3+ with no music playing, I hear a very feint FM radio interference. The other night I was hearing Kelly Clarkson Most noticeable are drums.

I never hear this interference except at full volume, I've never actually heard it during real listening, but I can't help but think its degrading the signal still.

It's definitely coming through the USB. If I turn off my PC, turn off or unplug the DAC, the radio noise is gone. If I skip the DAC and go from the PC's mini-stereo out to RCA theres no radio noise, but the overall sound quality is diminished.

The USB cable that came with the 151 has a ferrite core at the end, shouldn't that be helping?

I also have an Arcam A65 amp to B&W 602 speakers and I can hear the radio noise there too; although, the A65 is noisy at max volume so its much harder to hear above the hiss; Switching inputs on the A65 makes it go away.

Oddly enough, this shows me how powerfully resolving the WA3+ amp is, it's able to make a TINY radio interference signal sound crystal clear at max volume with no other hiss being added. Without the DAC its absolutely silent at max vol.

It might be moot since I have a DAC1 USB coming to me soon, but what do I do if I still hear this radio noise coming from that? My PC only has USB and mini-jack, so I'd have to get another soundcard to get an SPDIF output.

Anybody familiar with this?

[IctusBrucks]

Well I just replaced my Keces 151 mk2 with a Benchmark DAC1 USB.

I didn't even swap the power or USB cables, I used the same ones that came with the Keces so I really just unplugged the 151 and plugged in the DAC1.

With the DAC1, there is absolutely no radio noise

I was really expecting it to be coming from the PC, but it can be one of two things from my perspective:

1) The PC is actually causing the noise, but somehow the 151 passed it through while the DAC1 did not.

2) The 151 itself was responsible for the noise.

Next I want to test if the Keces 151 still makes the radio noise when plugged into a laptop running on batteries.