"I'm willing to bet that SOME of these units have line stages that are VERY similar, or perhaps exactly the same as those found in Krell's stand alone line stages of the day (which still sell for a VERY pretty penny.)"
Possibly but I wouldn't count on it because most AV processors that I know of use multi-channel electronic volume control integrated circuits and signal processing to handle multiple channels simultaneously.
A simple 2-ch preamp can get by with a simple analog volume pot or a simpler electronic stepped attenuator. They typically sound better as the volume control is a key element in how a preamp sounds. But who knows, the end result might be OK in an AV processor. However, in my experience they are -usually- not that great for 2-channel use compared to a 2-ch preamp.
If I were in the market for a Krell preamp on the cheap I would look to the KAV-280P. They're available in black or silver and to my ears they sound slightly better than the highly regarded (and older) Krell KRC-HR. But either of these may be available in your price range. I owned the KAV-280P for a while and it was very good.
