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It didn't work without glitches. We still encountered ticks and loud pops at irregular intervals. As though that weren't enough, we also had a fairly loud high-pitched beep. Otherwise the sound was uninteresting and thin. Using an iPad as spectrometer, our beep hovered at 8kHz. We checked all cables, the PC and NOS1 with their el-cheapo cords connected to a dedicated zone of the PS Audio Powerplant Premier.

Our preferred split file size setting, memory organization and file handling.
The Ncore power amps connected to another zone just like the active woofers of the Avantgardes. The interconnect between DAC and amps was a decent Hypex XLR cable.We also checked for DC between PC and DAC. The Phasure NOS1 DAC has two meters powered by an external 9V battery. When not playing, these meters should display around 2.4mV. So we asked Peter for clues. He pointed at a nice ground loop for the USB connection as our 8kHz tone matched USB 2.0’s asynchronous protocol frequency. But the real reason for most PC-related noise and problems arise from the PC itself which puts a DC load on the USB connection. That propagates nicely to whatever sits behind it via the ground connection of the mains.

 

When the PC booted up, things got worse. Disconnecting the DAC was no remedy. DC control over the meters went unstable. It's food advise is to keep the power amps switched off whilst the PC boots up. To counter our problem Peter pointed us at a thread on his forum: "Many times I've posted about noise problems I experience once in a while. This is another such post. It's all about that it can happen to you just the same but you wouldn't know it. I have an analyzer at hand to know instantly or at least check things a normal listener wouldn't. He would just perceive lousy sound and not know why.
"So I was away for 3 weeks. When I got home the first thing I did of course was switch on the amps and system, heat it all up and at long last listen to decent sound again. But it wasn't to be. Since my amps need some 24 hours to return to normal after being off for a day let alone 3 weeks, I thought it was that. Yet it wasn't. Working on some DAC ideas the next day, I noticed great distortion on my measurements but since this was about a new idea, I wasted a whole day getting that right whilst in the end the normal situation measured just as bad. What had happened?
Volume can be set per album to be consistent. There's no compression at all.

"I still don't know. All I know is that some huge noise from the mains or through the air using protective earth made it worst to be up about -40dB. Two days later I noticed that one of my devices was off though I didn't recall having shut it off. So I looked closer and saw that it was still switched on but not working (this was my FireFace 800 interface). Did it die by accident, from lightning or some other dangerous incident? Was something else down without me knowing yet?
Sound quality parameters where Q1 is the most important when kernel streaming engine #4 is used.

"In any case something had happened whilst being away and now I had find out what. I plugged my analyzer into the mains without PE (otherwise it would measure noise natively because it receives noise itself). I measured the analog outputs of the NOS1 which were far too noisy, about -80dB which should have been -113dB. Yet the NOS1 itself wasn't connected to the mains at all. This is dangerous because now everything was out of (ground) control.

Conversion settings with 16/44.1 to 32-bit/705.6kHz.
"Next I plugged the NOS1 back into the mains again without ground. There’s the on/off switch with double poles. Hot and neutral both were off. Nothing connected to the DAC proper. Behind its mains inlet sat the transformers and behind those the PSUs. But the PSUs were not connected to anything. Since the mains switch was off and earth disconnected, there shouldn't have been any connection. The only link was the cable's ground connection with the wall. There it stopped because that outlet was ungrounded. Yet by simply inserting that cable noise increased to truly unacceptable levels.

"Thus there was the ground wire in the 2m long cable connected to the case which connects to nothing at all since its internal ground floats. The interconnects exiting the DAC connected to the analyzer so what happened there was unknown. In any event plugging in the mains cord to the DAC drove up noise significantly. In my view this could only be picked up from the air. It could have been a combination of the AC ground wire acting as antenna and/or the Faraday construction of the case. If in the same situation I plugged the power cord into a grounded wall outlet, noise increased to minus 40dB.
Conversion setting with 24/96 to 32bit/768kHz.


"What I expected at that time was something very nasty on my mains which powerfully radiated through the air. The FFT of both situations (power cord grounded or floated) looked identical yet the former's noise level was some 40dB higher. The simple message is, this could happen to you too but without analyzer you wouldn't know why. You'll simply have bad sound. One day it could be fine, the next all wrong. Or it could go unnoticed altogether in your absence. Suddenly the sound is all wrong but you'll be clueless because you lack proper measurements from before. Perhaps 7 years later when you suddenly replace your TV, all will be right again."