Quote:   Yup! Thank you for your help :)

Recevied the USB isolator today and it appears to eliminate the problem completely! :)   I guess that confirms the problem was ground-loop related..?

Quote:   Yeah it does work fine with just the battery in the hornet and the DAC. Also, it works fine with the power supply connected to the hornet as long as I'm using a battery-powered source (like my MP3 player).   Unfortunately I couldn't find any circuit diagram for the amp.

Quote:   So a ground loop can't somehow cause USB disconnects? What tests can I perform to pinpoint the exact issue?

So I tried the set up on my home computer and with two different power supplies (yes I know I'm changing a lot of variables here, but bear with me :P)   With the first (cheap) 12V power supply, the DAC would repeatedly get disconnected from the PC whenever I plugged it to the amplifier(!)...

Quote:   I don't have the original power supply so I have been using another 12VDC supply. I've tried two different power supplies which both resulted in the loud noise. I'm wondering what are the DC Voltage tolerances for the Hornet though - perhaps it's really picky?   Quote:  ...

Quote:   Ah, so you think the problem is with the DC adapter plugged into the amp? In which component, exactly, do you think there's a poor implementation? Any suggestions on what to do to resolve it?

I disconnected the DAC and instead touched the amp chassis with the ground part of a USB cable. This reproduced the loud siren noise. I also tried a different 12VDC power supply for the DAC but the noise was still there.   So to me it appears that USB ground is noisy which is somehow picked...

Hi,   I've got an Emmeline "The Hornet" by Ray Samuels Audio amplifier. It has the option to run off a battery or with a 12VDC regulated power source. So far I've only used it with my battery-powered MP3 player, running on a 12V power supply.   Now I recently acquired an ODAC to play...