I may be interpolating a bit, but when you say you want surround, are you talking about surround sound for movies or surround only for SACD? The SACD 5.1 format is not the same as the DTS 5.1 or Dolby 5.1. If your SACD player is a DVD player as well, those 6 line level analog outs may be SACD/DTS/Dolby. You are, as others have observed, best off staying away from the outputs on your TV, and using outputs closer to the source, whether that is the DVD player, DSS/CATV box, whatever.
If the analog outs are SACD/DTS/Dolby, you might get away with running L/R front into your existing 2CH pre, the question is what to do with the others. On the cheapo side, you could run them into a HT receiver and use the outputs off of that--you could just mark where the levels are appropriate to balance the sound from your existing 2CH system and the new HT preamp.
Here's the dumb part. If you get an HT processor or receiver, you may be able to run digital coax or toslink off the DVD/SACD instead of using the analog outs. That won't, however, allow you to decode SACD through the same outputs, since the digital format is different.
If the analog outs are SACD/DTS/Dolby, you might get away with running L/R front into your existing 2CH pre, the question is what to do with the others. On the cheapo side, you could run them into a HT receiver and use the outputs off of that--you could just mark where the levels are appropriate to balance the sound from your existing 2CH system and the new HT preamp.
Here's the dumb part. If you get an HT processor or receiver, you may be able to run digital coax or toslink off the DVD/SACD instead of using the analog outs. That won't, however, allow you to decode SACD through the same outputs, since the digital format is different.