High end stereo preamps? Worth it?

A great pre-amp can improve the entire system.  Especially in hi-end systems.  It was a day and night experience to drive my power amp with my DAC vs a matching pre-amp.  The power amp has such a low impedance that the DAC literally collapsed on it.  The DAC was never able to play loud.  The pre-amp on the other hand can drive the power amp until the speakers melt. 

Some more really excellent posts about how a quality Pre amp with system synergy absolutely enhances an already fine rig.  But to my point about not being able to site examples of science, I guess I meant that it is not easy 'to measure' the difference.   Nay sayers seem to stick to this defense; 'if you can not measure it, I can not hear it' and 'bits are bits' etc.  And, quite possibly, they can not hear it!  To me, measurements are important, but hearing is believing.  

Given high output voltages of modern DACs, the Pre becomes a glorified attenuator. The same result is achieved by either buying a DAC with analogue volume control or using a passive attenuator. There is really no good reason to use a Pre in digital playback. Analogue however is a different matter...

so a preamp bought to be used in ht bypass mode and only streaming from a nucleus is not needed, ie. Of no value??

@antigrunge2 

Given high output voltages of modern DACs, the Pre becomes a glorified attenuator.

This was a common viewpoint a few years ago and continues to work well for some, but others who have tried running their systems DAC-direct or through a passive preamp have perceived a loss of dynamics and tonal density and have since gone back to using preamps or buffers.  If you take a look at my post from noon yesterday, you can read about other factors that affect sonic performance with/without a preamp that go beyond simply having adequate voltage to drive the amplifier.  BTW, digital becomes analogue when it comes out of the DAC.