High end stereo preamps? Worth it?

Only if you have an income 10X the price of that expensive preamp! It's really only jewelry!

I have limited owning experience but did a lot of research on preamps. The Quicksilver Line Stage, non-remote, version, is very simple, point to point wired, very good customer service, and has a very good reputation with customers. The company does not send units out to reviewers and is made in California. It's $1500 new but can be had for close to $900, used. That is, it seems to me, an extraordinary value in audio. 

+2, soix.

Once you hear Luxman, Accuphase, LTA, CJ, VTL and Shindo, you will know exactly what you were missing in your music.

BTW, Accuphase Integrated have an option to add phonostage and DAC modules.

In a highly resolve system, everything matters not just a high quality preamp.

Yes, they are, in answer to posted original question.  But the dac direct is a nice fallback if cost prohibits getting a good preamp.

@fastfreight 

In each setting, the overall sound and especially soundstage was improved by inserting a preamp.

My experience exactly after trying multiple types of passive volume controls and DAC direct to amp approaches.  I am using a unity-gain buffer, so no gain like a traditional preamp but active buffering of the signal, which seems to preserve the tone and dynamics that I find missing with passives and DAC direct approaches.  To answer the OP, "high end" preamps presumably handle the signal better than lower cost approaches (i.e., better design, better power supply, less shortcuts, better parts) but more dollars don't always equal good sound so to your question of "High end stereo preamps? Worth it?" my answer is, having a preamp or buffer is better than having none, but to the value - it depends on the preamp.