Actually, from my kernel work, and from reading the DSP specs, I think that you're wrong here...Of course, part of this is guess work as I've never signed an NDA to be able to see the programming info for the DSP.

dB is a relative unit, and has no meaning without a reference level. In the case of an analogue signal, we could state that our reference was eg 1V, and then -3dB would be 0.5V, and +3dB would be 1.5V. In the digital domain, once all of the bits are 1, you cannot get any higher, so if you did state that this level was your 0dB reference point, then only negative dB values make sense, and any signal that attempted to exceed this value would indeed clip, as you have alluded to.

In the case of the empeg, 0dB in the player domain does not *appear* to be the maximum volume level that the DACs can handle - but near the point where the THD in the DACs is lowest.