[Budo]

Hi there, I'm wondering if anyone has the same experiences as I have had using NuPrime's equipment.
Configuration:
Stream 9
DAC-9 SE
AMG PRA
AMG STA (2x mono)
Cables: Cardas Clear Cygnus xlr
Martin Logan Masterpiece classic ESL 9
Powerconditioner: Audioquest
BOTW for feeding the ML's
Polarity checked

Issue:
Playing a song via Qobuz, High res. with power Stream-9 and Dac-9 SE set to Max., Volume control PRA set to 25, SRC PCM 768, interconnect IIS. Song is Carry my hart by Indra Rios Moore.
At certain frequencies there is a prominent hiss from the speakers. I've exchanged them for my Sonus Faber Cremona's, there the problem existst.. Anyone any idea?

[rustydoglim]

Hiss from a particular song? Perhaps it was there all along.

[Budo]

I recently completely changed my audio setup, in the previous one i've played this song many times, without any hiss/noise at all. There are more tracks on witch hiss occurs, for example Lizz Wright's Hit the Ground. The only thing I know so far is when I when i turn down the volume of the Stream 9, it's all gone. So, there is a practical solution, but let's be serious, this shoudn't be the case with such high grade equipment.

[worldcat]

STA has hiss

[rustydoglim]

AMG STA has even order harmonic by design from the class A transistor input stage, so if your speaker is high efficiency, then there could be hiss.  We have another customer in the US with this problem, but we can fix it by changing a small component. That would require a trip to the service center.

[Budo]

Not shure what you meant bij "high efficient". Sensitivity is 90dB/2.83 V/M. And, as I mentioned, the problem persists with different loudspeakers. Btw: played the forementioned songs driven by my PrimaLuna valve amplifier, (even harmonics!) without any hiss or distortion.

[rustydoglim]

Why don't you create a help desk ticket and let support figure out what's the next step.

[rustydoglim]

This is the comment from our chief engineer:

The customer turns the source to the maximum volume, so he can hear the bottom noise or switching noise of the source.
When the volume of stream 9 is 100%, the maximum output is 2V RMS, DAC 100% will be amplified by 2.5 times.
Just set the source volume, stream 80%, dac 70%, will be more correct.

[Budo]

Thank you Rusty and chief engineer! Now I know that the cause of the noise lies in the NuPrime equipment. This work around solves all the issues as I already found out. Idea to fix this for future product releases, or is it a result of the combination of equipment/setup?

[rustydoglim]

According to Chief engineer, the problem does NOT lie within Nuprime equipment.

he customer turns the source to the maximum volume, so he can hear the bottom noise or switching noise of the source.

Noise exists from the source and if you purposely set the GAIN to maximum, then you are amplifying the noise as well.