High end stereo preamps? Worth it?

chorus

In a blind test no preamp can improve upon no preamp.

That’s an interesting claim. Have you actually conducted such blind tests? If so, please provide details and include the other components used in the test system. Then perhaps we can tell you where you are going wrong.

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??