I've begun trying a variety of external DACs with the Squeezebox and I'm
attempting to compare the Squeezebox analogue output with the DAC outputs.

In order to do this, the output level needs to be set the same so the listening
tests are not compromised.

So, I did some measuring.

I created a file of white noise with a level of 0dB (using Steinberg Wavelab)
and set it playing on the Squeezebox. I then measured the voltage at the
analogue outputs of the Squeezebox, an Arcam delta Black Box 5, and my new Art DI/O.

Now, 0 dBu is defined as 0.775V so I've referenced all my measurements to that
level.

Here are the results;

Description             Voltage (V)  level (dBu)
Reference level (0dBu)        0.775        0.000
Squeezebox                    0.440       -4.917
Arcam                         0.800        0.276
DIO                           8.400       20.700

These are approximate values as white noise does not produce a steady signal so
I've guessed the voltages at around the maximum of the values I was seeing on my
voltmeter.

Key points to note:

1. The Arcam is pretty close to the 0dBu reference - in fact, allowing for
measurement error, it is pretty much spot on.

2. The DI/O has a specified output level of 20dBu. Again allowing for
measurement error, it is pretty much at that level.

3. The Squeezebox is nearly 5dB lower than the reference level (0dBu). This
would explain why several people have complained that the Squeezebox seems
quieter than their other hifi components - that's because it is!

Is this a firmware issue? Or is this an inherent limitation of the Squeezebox
output electronics? (I tend to think the former as there are no output
electronics in the Squeezebox - all the processing and audio control is pretty
much all done on a single chip).

Thanks,

R.