Well heres the think. The trick here, and what makes it unique and sound the way it does is having the signal into the PA arrive AFTER the amp's signal has already been heard. Even tho it's just double digit milliseconds the human ear detects the difference and it gives a huge sound. If the dry signal hits the PA then hearing that at the PA at the same time as you hear the note at the amp completely erases the effect. So i'm not sure what delay you are using, but you have to see if it's capable of that. Any delay thats stereo should be. See if the unit has a wet mix only or if the mix know when maxed out gives only wet signal. You can test it by plugging into it and out to a amp then setting it for wet only however you have to, set it to a very long delay, preferably a second or more. Then play a not and if you hear nothhing till a second later then it's set right. Then when you try this you want to set it somewhere between 30 and maybe 60 or 70 Ms at most. The more you use the more huge it will sound but the tradeoff is it will sound more and more overly processed as you make the time longer. Too much and it will get confusing. Also, the way you want to set the level is use a second delay again just to test it. With the PA set where it's going to be for the gig and a good second of selay, play one note and listen to the volume coming from the amp and the volume coming from the PA. Set the PA channel you are going into so the note that comes from the PA is the same as the amp, preferably just a bit less so the delayed note doesn't sound louder to people who are sitting closer to the PA speaker than your amp. Best thing to do is test this at home using a second amp as the PA, or anything for that matter,. Into a computer using it's speakers, into a stereo, etc. Whatever is available. Then you won't have to rush to get this right at the gig.