[Meindert Sprang]

"w_tom" wrote in message
oups.com...
Now once those untwisted wires are disconnected, the computer may
then report the disconnect. But that is also useful information. USB
detection for connection, bus speed, and disconnection are all
performed on the signal (twisted) wires.

Yes, but in conjuction with the power wires. From VBus drives internal
circuitry which in turn injects for instance +3.3V on D+ to indicate a
device is full speed.. Without the presence of VBus, the device will not
send ANYTHING on the data wires and will therefore not be detected. And
since the Ground wire is needed to reference any of thos signals against,
cutting either wire will report the device as disconnected. Apart from that,
cutting the ground wire of the usb cable alone, is makeing the entire supply
current of the device through the datalines with will be detected as a fault
situation in the host port which will be shut down.

If both boxes have their own
power, then voltage power on untwisted wires is not necessary.

One had, the other didn't. And as you could have read, cutting the VBus wire
to the Alesis did also 'disconnect' the device.

Removal of that unnecessary power should cause no disconnect detected
when untwisted wires are disconnected.

Wrong by the USB standard, proven wrong by SoundDog.

You now better stop making a fool of yourself by constantly ignoring and
denying expert advice.

I am not lost.

We are. If SoundDog tells us that even the bus powered device produces noise
on a headphone, there are no groundloops anymore that could cause this. If
computers swapped still produce the problem, it cannot be the computer.
Besides, the sound in the computer is digital, so interference in the
computer can affect that data and not crash the computer. Power supply noise
of the computer cannot affect the digital datastream. There is something
else going on which we are not told yet.

Meindert