Here's what he said:

"Hello! Anyone know the actual level of the internal calibration test tone on the 990? I mean, if I put the master level to 0dB, the tone that is output must somewhat be equivalent to an actual level on a digital media, say a DVD.

I seem to recall that these tones are usually at -20dBfs or -30 dBfs.

Thanks!"

The fact that he mentions dBFS (decibels relative to full-scale) is the terminology that is used to describe the magnitude of a digital file. Also, that he cites the two values as negative (-20 dBFS and -30 dBFS) makes sense; in a digital file, 0 dB equals full-scale, that is, all bits hi. Therfore, anything that is less than full scale will be, by definition, signed as negative.

Therefore, as I interpret it, he's asking about the magnitude of the test tones as if to say "are they (the sett-up test tones generated by the 990) of similar magnitude as what would be found in other media".

The level that is reproduced from an audio system, using a digital file as its input, depends upon the scale of the file itself (i.e. how many dBFS), the gain of the preamplifier, the gain of the power amplifier, and the sensitivity of the speakers (as well as the room in which they are placed and the acoustics thereof), and where the pressure is measured. Thus, the level of the test tones cannot be stated in dB SPL (that is, dB referenced to 20 uPa) because it's meaningless - it only makes sense to describe them in terms of dB relative to full-scale. The 75 dB(C) value that Outlaw cites in the manual is the dB SPL value suggested such that it will have a relatively high signal to noise ratio (in a typical home), as well as being easily heard, yet not offensively loud.

Again, the "actual level" (as he put it) can only be expressed in dB relative to full scale, because that's the only scale that has any relevance in a digital file.