Adding pre-amp to an integrated amp?

Perhaps this it what they are referring to; some integrated units have a set of U-shaped pins that can be pulled out. When that occurs the amp/preamp can be used independently of each other. In that case, a better preamp could result in better sound.

I agree with LAK. I doubt they are double processing the sound. Some integrated's also have an additional pre-out so you can add a second amp and Bi-amp using an integrated. NAD, Cambridge Audio, and Rotel's for example.

Nope. They are using the same integrated amp as mine. It don't have a pre-out. To my understanding, the immates just plug the output signal from the pre-amp to any of the inputs of the integrated amp. This resulted in double amplification of the signal. That cause my posting of the questing.

Siulau: Are you using an amp that only has a single volume control (the only control on it) and which only accepts one line source? Better yet what amp are you using? I have tried a few active preamps with my Audion Silver Night stero 300B amp (which has a single volume control, an Alps, and that's it). I tried setting the volume on the amp at between 10:00 and 2:00 on the dial (which should be its optimal range) and got different, but not better sound. I seemed to lose the micro details of the amp (on its own) in exchange for added flesh, dynamics and a slightly wider sound stage (which may be what you are looking for). I had thought that because of this I may want to try a passive preamp next (though I cannot afford the ones that look good to me at this time) to see if one would make less of a change to the sound of the amp. I would like to add switching capabilities (like add a CD changer for my wife to use and maybe even a turntable at some point) which is why I even tried the preamps in the first place, so our goal is not the same. I do not really consider the Audion to be an integrated amp, just a power amp with a simple gain control (volume pot). The pot itself may be passive for all I know as I do not know much about the design of the unit.