I need to run my signal from the effects loop send of my tube amp into a series of effects that use balanced inputs/outputs, then pack into the effects loop return. I know I need a DI between the send and the first effect, but what should I use to bring the signal back down to line level for the return?
You Shouldnt need a DI in the chain. First you need to make sure your amp have a Balenced FX loop. Most amps have Mono FX loops,

The only thing u need are balanced cables. Meaning EVERY cable in the FX chain. If every cable in your chain is balanced, that is all you need to achieve a balanced siginal.

If your amp FX loop isnt balanced you should look for another DI with line level convesion from the Last effect back to the amp.


Two of these should do the trick.
Framus Cobra
Marshall JCM 900
peavey 5150

Mesa 4x12