OT: Tube Audio

OK, since there seem to be a fair amount of people into Tube audio, or at least with a knowledge of it. Would someone care to explain the following to someone that is used to an all in one unit such as a Sony Receiver. What is the purpose of separate Amp and Pre-Amps. I think I understand the whole phono pre-stage, but I've yet to find a decent explanation of the rest, and I'm looking to switch to tubes for playback of records (primarily Vinyl, but I'm also interested in 78's). Zane -- -- | Zane H. Healy | UNIX Systems Administrator | | healyzh at aracnet.com (primary) | OpenVMS Enthusiast | | | Classic Computer Collector | +----------------------------------+----------------------------+ | Empire of the Petal Throne and Traveller Role Playing, | | PDP-10 Emulation and Zane's Computer Museum. | | http://www.aracnet.com/~healyzh/ |