The best "setting" is "setting" it down and picking up that Explorer!
Just yankin' yer chain Tony,my modded IDXPro will hit a 9" silver dime pretty effectively with the 950 coil...BUT!.......the soil must be perfect! If it's mineralized,BYE BYE depth. This is where FBS steps in to take over,it's MUCH better at finding that type of target at the depth you want in that soil,usually. I'm normally very "diplomatic" when talking about my IDX and the FBS in the same thread,the IDX is very good at what it's good at. Getting an initial hit on a really deep old coin in bad ground is not one of its fortes,IMO. Again with the diplomacy! But it's true. Targets to 6-7"? The IDX will hammer them all day,junk or not. But ALL of my old coins are DEEP,so I use the CTX the most.
In one of my best parks that has historically given me some of the coins that people hunt for 30 years for and never find, the EMI in one section just swamped my Explorer2. This was before I had the CTX. I took the IDXPro down there and with the Frequency Shift was able to tune out the noise. That day I found a Rosie,Merc,huge deep token and a 3 cent copper nickel,1865. It was next to a piece of junk,but I knew there was a good target. This again is using the 950 coil. I believe I decided to dig the coin because I know the IDX that well and KNEW it was onto a coin through the quality of the tone. Experience counts for ALOT,you know this as well as anyone. But if the machine isn't capable of giving the initial response so that you can start to "interrogate" the signal,it's done before it starts. This seems to be about where you're at with your testing....