Direct Stream DAC mild humm noise

I bought BHK 250 recently and hooked on to KEF R3.
I enjoyed the music with so much clarity and dynamic, I love it and enjoying it.
I played music from A&K SP1000 and connected to BHK250, it is fantastic.

So I wanted to add DirectStream Dac to the family to get to next level.
I have connected my DS DAC and BHK250 using RCA, while I am waiting for my RCA cable get delivered.

I used Mac as source and used USB input, I found bit noisy, I so I tried Audirvana (got to know from Pauls video) it worked well, still I hear some noise.
Then figured out how to play connect A&K to DAC unfortunately, I still hear hum noise, so I attempted to figure out the source of noise.

First step, I removed input source from BHK250 it is silent, so BHK250 is ruled out
Second, connected DAC using RCA again and turned off DAC using remote, still noise persists
Then turned off power supply switch in rear of DAC, still I hear noise - I suspected power supply cable
I swapped stock power cable with “IsoTek Evo3 Optimum”, still no luck - noise persists
Finally unplugged power supply from DAC - noiser disappeared.

So, based on my analysis, I see the noise is coming from DAC.
I don’t know what I am missing, but love to get rid of the noise to enjoy the music.
Love to hear any recommendation from @tedsmith or @Paul

Thanks for reading my experience, tiull the end.

Note: Power supply is connected directly from wall socket
RCA cable: Van Den Hul Minisub Hybrid Cable 3.0m (HALOGEN FREE)

Out of curiosity, did you try a pair of XLR cables between the DAC and BHK, it might possibly solve your problem.

Once my XLR arrives, I will try connecting DAC and BHK250 using XLR

I’m going to guess the hum will become pretty much silent once the XLR cables are running between the DAC and the BHK 250.

Question please: What type of digital cable are you using between Astelle & Kern SP1000 & PS Audio DSD?

USB in Audio mode

Sounds like a ground loop to me. Try a cheater plug on the DAC, I bet the noise will go away.

Hi Arun,
Good to know. I have always thought the USB 3.0 port on the AK SP1000 was for data transfer only (PC / MAC). So, could it double up as digital output? have you tried using the 3.5 mm optical output?

I ordered optical cable, most probably it will arive tomorrow.
I will check and let you know how it goes.

One more info: AK SP1000 Usb can be used as dac, so that audio from mac can be pass through AK and you can use 3.5 mm as output for headphones, etc

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A&K players have good DAC chips inside.
Happy listening.

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I got the optical cable today and used it, optical output produces better sound compared to usb but still I see the humm noise

Hi Arun,

Sorry to heat the problem has persisted. a) is the noise emanating from both channels? b) Does the hum change if you touch the body of the power amp or the DSD? c) have you tried the RCA cables to connect any other device to the Power Amp?

Hopefully, you will find the culprit, and sort the issue soon. All the best.

I have been using that rca cables in my SVS-PB16 subwoofer for a while it was ok.
I used another RCA cable connected from AK SP1000, to BHK then to Kef R3, it is fantastic, I am enjoying that setup.
I seeked help from retailer, they asked me to reduce/increase volume and also changing settings in DAC , by changing the volumne level to “Low” even that didn’t help.
He also offered to lend me some RCA cable to test it
I don’t see any difference if I touch either Amp or Dac
Currently, I am keeping Dac and Amp in a rack, he asked me to keep both of them away from each other.
Let me try that option too, see if it helps

Yes, both the channel exhibits same level of noise

Please bear with me Arun, what type of plug does your system use? US, UK, Schuko, Aussie?

Aussie, no worries

So, removing the ground prong to test for ground feedback is not an option.

Weren’t you giving XLR cables a try? I’ve found PS Audio gear to be quite a bit finicky with ground loops and RCA cables.

Yes, I’d be curious if it goes away when using XLR between DAC and amp.