[Bullseye]

Hey there,
 
I currently have the Cute Beyond headphone amplifier. I am happy with it except for the  hum/noise I get due to the power supply (ground loop). 
 
I also have the Little Dot I+ and with it I don't get that background noise.
 
I am not looking for any "sound flavor", in fact I am looking for the one with the most linear response under a low impedance load. Being the most important that it doesn't have any background noise when turned on with headphones connected.
 
So far I have as possible the Audio gd Fun or C2. I haven't been able to find any RMAA for the amp section of any of those, but for a similiar price I'd go for the FUN due to the DAC. I haven't read nayone complaining on any of those regarding background noise.
 
As source I use my Zune HD + Dock (has RCA out and optical). I prefer to use optical rather than analogue, but with my sistem now I can't use the former due to excessive background noise.
 
Before I decide to buy either of those products mentioned I'd like to know if there are other products similar in price (~$400-$500 shipped) that will provide me with what I am looking for (linear response and no background noise). 
 
I'd also appreciate personal opinions related to ground loop issues or similar with any of the products listed.

 

[Bullseye]

Bump for some help

 

[jdkJake]

Ground loop? How do you have a ground loop? 
 
I am unfamiliar with the Cute Beyond. How is it powered?

 

[Bullseye]

I have ground loop because the power supply doesn't have ground connection. It is similar to the one on this picture:
 

 
Quote:

Ground loop? How do you have a ground loop? 
 
I am unfamiliar with the Cute Beyond. How is it powered?

 

[Bullseye]

So? No one knows of any other contenders around that price?

 

[jdkJake]

Quote:

I have ground loop because the power supply doesn't have ground connection. It is similar to the one on this picture:
 

 

 

I think you need to look elsewhere to find the source of your ground loop. The power adapter just provides 24V DC to the amp.
 
What do you have it hooked up to? Suggest the source of the hum is further upstream of the amp.

 

[Bullseye]

Nope. I have located where the HUM comes from, and it is from the power adapter. As I mentioned it doesn't have ground connection. 
 
When using the Little Dot I+ it doesn't happen. I have also had other issues related to ground connection with other products, and it has been solved by connecting the power source to ground.
 
Quote:

I think you need to look elsewhere to find the source of your ground loop. The power adapter just provides 24V DC to the amp.
 
What do you have it hooked up to? Suggest the source of the hum is further upstream of the amp.

Even so, my question remains unanswered. Any other products I should consider at that price range?