Yo Mike:>
This is kind of tough to explain but once you get into the group mode, it gets easier.
You push the silver button down which is the group select button and then you push down the track/tracks you want to record. You should get an indicator light in the BOTTOM ROW OF LEDS, ONE DOWN FROM THE "DIRECT RECORD" LIGHT.
Now you can enter the bussing world. {someone out there posted a clearer version of what I'm trying to say and I have a copy of it at home, which doesn't help me here at the office.}
Let's just say that you want to run your drums[drum machine] on two tracks to get a stereo/or double mono effect. Well the 1/4 inch plug from the drum machine goes to input track 8; now, when in the group mode, you can push one of the 1/2 or 3/4 buttons and you can buss your drums to a second or third or even fourth track. Just play with the buttons and you will get there.
However, remember, YOU WILL GET NO SIGNAL RESPONSE ON THE TRACKS YOU CHOOSE UNLESS THE "RECORD" BUTTON IS ENGAGED ON THE MD-8. This drove me nuts for about 20 minutes when I started to experiment with bussing and group recording. In the group recording mode, you can also put in effects while recording if you want to/or add them during mixdown.
So, what ever you plug in, a mic or your keyboard, you can route it to about any track or tracks you want. There is something about the odd/even left/right and it applies when you start to push the 1/2 & 3/4 buttons to do the routing.
One nice thing about the Group mode is you can route your vocals from just one input to two tracks. Then, you can pan a little and get a nice stereo effect.
Hope this helps out Mike; I learn every day when I turn on the MD-8 and from the nice folks who pass on their expertise on this site.
Keep twiddling the dials,
Green Hornet