i have a pair of paradigm titans, but I may upgrade them to monitor 7's in the near future.

i've been looking at vintage amps- like fisher and marantz, many are over $1000. does anybody have any suggestions that can get me rocking tubes for around $400? i also don't really understand the concept of pre-amps. are they necessary? does the pre-amp have to have tubes as well? something i've imagined would be a modern pre-amp with s/pdif coax connectors (does this exist?) paired with a vintage or at least utilitarian tube amplifier. i don't need fancy looks- just great sound.

also, i've seen on ebay- tube amplifiers that have been re-moved from jukeboxes, some dating back to the 50's that have been re-capped. are these any good for audio reproduction in a stereo system?

thanks for the consideration to those who provide responses!