This may sound a bit silly but why are so many

Ok its a reference preamp at least that is the label given to it by Audio Research. Doesn't mean that it is leaps and bounds better than what it replaced. Maybe there was no improvement at all and if there was, maybe it was just marginal and resold. A couple of months ago I listened to the new top-of-the-line Reference Audio Research system, connected to Wilson speakers. It had a combined cost of one hundred thousand dollars. I walked away unimpressed and thought what I had at a much lower cost sounded better. Sometimes the law of diminishing returns does apply.

Tomcy6, I think your post nailed it and believe what you said covers most all what I think is true when it comes to buying and selling.

Mich4t, you are correct that a sale of a preamp can be the result of wanting the new and improved model. To this day I can't understand why the AR reference system I listened to did not move me. I asked the dealer to try a different CD with no improvements. I thought also that the Wilson speakers could quite possibly be a bad match for the audio research components.