Berkeley DAC into preamp or amp ?

I've done some searching but don't see many comparisons of the sound of the BAD Alpha DAC fed through a preamp versus into the amp directly. I'm interested in the degree/range of digital attenuation needed with amps of various gain. At what attenuation level did sonic degradation (if any) become audible?
I recently tried the Berkeley running directly into the amp. My experience has been that such a setup always flattens the depth dimension of the soundstage, and this was no exception. In my opinion, any minor improvements over an excellent preamp (immediacy and such) are not worth what I consider to be an unacceptable compromise. In my case, I need the preamp for vinyl in any event. The exercise simply proved what I had heard on numerous 'direct feed' systems previously.
Curriemt11 - that's been my experience too, at least with a couple of Wadia CDP's I used to own. As for the Berkeley direct, do you recall how far you had to attenuate with most music? (I.e. what was the LED readout, and did large attenuation seem to affect the sound?)

Rja - what amp are you using?
Ral - sorry, I should have mentioned that. Moderately high volumes were in the 50 range. I noticed no deterioration of the sound at lower levels, but then again, I rarely listen at those volumes.
I think the input impedance of the POWER amp side is a huge factor. Some amps will never work with a DAC directly.