It sounds like you want an analog preamp with a pair of preamp
output jacks and power amp input jacks on the rear panel, plus a tape monitor loop that will allow you to insert a surround processor. This configuration is available on a number of preamps, but perhaps not in the under $1k price range. There are obviously a variety of preamps you can consider, but based on your budget I'd urge you to consider the Adcom GFP-750, which can be often purchased used for about $750-800. I am not sure, however, if this preamp has the necessary rear panel configuration and tape loop monitor, but you can probably get more info from the Adcom web site, or from owners who post here.
output jacks and power amp input jacks on the rear panel, plus a tape monitor loop that will allow you to insert a surround processor. This configuration is available on a number of preamps, but perhaps not in the under $1k price range. There are obviously a variety of preamps you can consider, but based on your budget I'd urge you to consider the Adcom GFP-750, which can be often purchased used for about $750-800. I am not sure, however, if this preamp has the necessary rear panel configuration and tape loop monitor, but you can probably get more info from the Adcom web site, or from owners who post here.