I've just got ot chime-in to this old thread to counter Steve's experience above. I've had DEQX HDP-3s and always used them with external DACs, and never experienced the issues he described - never. The internal DAC is not "bad" but one can do quite a bit better. The conventional wisdom that the extra ADC stage would be a large detriment does not seem to apply - at all.
I find the room correction the least important feature of the unit, by a longshot. The steep, linear-phase crossovers and time & phase alignment can (and normally do IME) give results I would call "stunning". Then there is all the parametric EQ one could want. If one is DIYing a horn system, with PEQ and time-alignment necessary, I think it is impossible to do better with analog xovers, passive or active.
When properly used, the unit is completely transparent and does not have the slightest hint of anything "digital". (I think anyone who heard the Cogent True To Life field-coil horn system at RMAF 2006 would attest to that.)
I find the room correction the least important feature of the unit, by a longshot. The steep, linear-phase crossovers and time & phase alignment can (and normally do IME) give results I would call "stunning". Then there is all the parametric EQ one could want. If one is DIYing a horn system, with PEQ and time-alignment necessary, I think it is impossible to do better with analog xovers, passive or active.
When properly used, the unit is completely transparent and does not have the slightest hint of anything "digital". (I think anyone who heard the Cogent True To Life field-coil horn system at RMAF 2006 would attest to that.)