Can you give me some more information about your set up?
Are you getting a low input signal on the Eclipse with the series loop or parallel loop? Or both?
Which specific MESA Boogie amps are you using?
You mentioned that you are having issues maintaining levels between programs, is the low input signal issue always happening no matter what program you are using? Or is this changing as you change programs?
From what I’ve read here on MESA’s website all of their amps since the MarkIIC+ have buffered effects loops, so it should provide a hot enough signal for your Eclipse. https://mesaboogie.zendesk.com/hc/en-us/articles/226119347-Should-I-use-a-Buffer-in-my-amp-s-effects-loop-
I don’t think you would need to add a MixingLink in your effects loop to get the right signal level, how high do you have to turn up the gain on the Eclipse to get a decent signal level from the effects loop?