Hi,
to set up your power amps, you must measure and adjust.
For output offset measurement and adjustment you must fit a source resistance that, matches the only source you will ever fit, or set Rs=0r0 for test and then recheck when you connect the actual source and also check what happens when you turn ON & OFF the source while the amp is powered up.
In a parallel arrangement, DC output offset is critical. To minimise the risk of this biting you I think the set up must be AC coupled for each of the paralleled amplifiers. Set the DC output offset to be equal when ALL THE CHIPS ARE COLD.
Then add a DC servo to each of the chips to ensure the DC offsets remain equal while the chips warm up to operating temperature.
If the input offset currents and input offset voltages are compromised by choosing different resistances to feed the +IN & -IN inputs for ALL the chips then you will have further problems with keeping output offset low enough to avoid the problem all beginners have when trying to copy bad schematics of parallel implementations before they have learned what the chipamps are designed to amplify.
Beginners.
Build single AC coupled chipamps and learn the subject before progressing to more complicated arrangements.
Ret,
you have hit precisely this beginners' quandary.
Build a single AC coupled chipamp. Build 4 of them. Have you learned why and how they work?
Now the big jump, let's join them together using a bad schematic before one has learned to read and understand what is bad about that schematic.