At my friend's studio where I use the M2600, there's a Roland SDE-1000. Since all the aux sends are used up for other things and I don't use the buses for anything, I use a bus send to feed the delay, then return it to a channel where I can apply eq, add reverb via an aux send and route it to any monitor mix. The drawback to the bus send is that it's on or off. But since I typically use it on one input at a time that's not a problem. I just use the return to control the level (and set all the aux sends on that channel to post fader).