Sorry for the late reply,been busy lately.
Change the pre's setting from standard mode to network mode from the switch that's attached to it's chassis.
Now you'd have 6 outputs,refer to the pre's manual by downloading the one for 8650 to see which RCAs do what.Anyways so you'd have highs,mids and lows.
The tweeters will need a 2.2uF or 2.5uF capacitor in line on the positive side to protect it from any possible damage and they will be run on the High channel.Next up is the midbasses which will run on the Mid channel and lastly the lows will cater to your subwoofer.
Run your amp in 4 channel mode,and on stereo.You'd need 3 pairs of RCAs now so basically you're giving each driver it's individual channel and a RCA.
Now comes the fun part, adjust the crossover points for the highs first.Your tweeter should start playing from 4khz upto 20khz,you can try uptil 5khz to see what sounds better.Your midbasses will play from 80hz to 4khz.
As far as slopes are concerned start with 12db slopes and move on to sharper slopes like 24db to see if the sound doesn't seem too tiny or doesn't blend it.If you're choosing a 12db slope between the tweeters and midbasses do flip the polarity of the tweeters from the network settings to see if it sounds better because 12db slopes cause a 180 degree phase shift so you flip the polarity on one set of speakers to bring them back in phase.This doesn't imply all the time.
Next is Time alignment and EQ plus level matching.
if you have the microphone that came along with the pre the process will do itself otherwise this is gonna be a pain in the back side.Start with level matching the drivers using a Uncorrelated stereo pink noise track.Mute and unmute each individual driver to make sure they're playing at the same intensity,do this in pairs.When you're done use a tape to measure the distances from each driver to your head,you should be fairly close now.For fine tuning,use a track with a centralized vocalist and only run one pair of speakers at one time,adjust the distance on the left side only so if the vocalist is too much right,increase the distance on the left speaker to move the image to your left and vice versa.When you're convinced that the image is dead centre now move on to the next pair and repeat.
Last but not least,the subwoofer...
measure the distance with a tape,use a track with a good bass guitar and TA till the sub sounds like it's in sync with the midbasses.It's hard to explain so you'd have to listen for the sound to be one note.Attenuate the sub so that it matches the intensity of the midbasses.If you're using a 12db slope on the sub as well then try flipping the polarity on the sub too to see if it sounds better or not.
If you have any further queries,feel free to ask.
Cheers...