Value of a preamp?

@yoyoma26  " the reality is that any source component that can drive a power amp effectively has a preamp in it. So it depends on how good a preamp you want."

Excellent point.  If your source already has an excellent internal preamp, you might or might not benefit from a separate preamp.   When people say that they do or don't get benefits from a preamp, it would be really helpful to specify what source, amp and speakers they are using.

I'm currently using a PBD MPS-8 without a preamp, using the variable volume control and XLR cables direct to AGD Duet amps, and YG Hailey 2.2 speakers.   Sound quality is excellent, but I'm curious what effect a preamp might have.   

@ddgtt

"I have discovered some great preamps out there and I’m happy to recommend them should anyone be interested."

I’m interested in hearing what you recommend. Are there preamps that you think will work with a variety of amps, or do specific preamps need to be matched to certain amps?

@yoyoyaya 

Christiaan Punter has a nice piece on the value of preamps, even in a purely digital system, and a comparison of several preamps.  

@ddgtt Have you heard any of the Aries Cerat preamps, and any thoughts on how they compare to the Stern and the others you listed?