amp head plugged into a combo amp??

whats the point in having a amp head plugged into a combo amp? Ive seen this a lot recently.

http://www.flickr.com/photos/21841951@N00/3025843175

Most times it's used as a pre-amp.

Couldn't you combine effects?

Louder Volume
Better Volume/Tone
More Distortion
More Fx/Fx loop
More in/Out-puts

As far as running an amp head into a clean amp channel I could see the appeal to having more tone shaping options with two independent EQ's(pre-post EQ). I use something like that with my pedal already and I can shape the sound all over the spectrum.

i have that kind of rig. i was looking for a good distortion and figured the best i can find was the distortion in my 80's Duncan 84-40 amp. i disconnected the speaker and basically used it as a head connected to my 77 bassman. since then, i couldn't find an amp setup that sounded better. the cool thing is that you have a whole new set of knobs and E.Q. to mess with to get the exact tone and sound that you want. and i even jumped the two channels on my bassman to give me even more knobs to play with.

sorry its kinda blurry, but you get the idea.

no its good, thanks a lot!!!