I'm using a Mooer Reecho in my VOX AC30CC2 effects loop. Running the amp clean, it sounds great. However, I like to drive my amp into a mild overdrive, but my Reecho can not handle this. The pedal does not have enough headroom to cope with the volume boost. What can I do to drive my amp and use a delay pedal in the effects loop at the same time?
Simple answer - attenuate your signal before if gets to the delay. I know you mention a -10dB attenuation on the AC30, but if that isn't enough just get an volume/attenuators pedal and pop it in the chain before your delay.
If you are more electronically proficient, you could try to alter your effect loop attenuation, but that will not be easy, and will mean future effects may suffer, so my recommendation would be to buy a pedal.