I fail to understand how a preamp can provide more dynamics to a signal. If it is altering the sound in some way, that to me is a completely undesirable trait. If you have a competently-designed DAC that is capable of driving the input stage of an amplifier directly (and assuming 24 bits used for digital volume), what possible benefits can a preamp provide? It can only add noise and distortion, it can't take it away. Certainly if a DAC cannot provide enough voltage to obtain the required volume, a preamp would be required, but short of that, I fail to see any point at all.
I suppose all of you who expressed a preference for a preamp in the chain have done ABX testing?
[I know I'm going to ruffle some feathers here...it's meant to be thought-provoking]