Yes.
The splice may add some minute resistance to ground.
If there is a ground loop issue it is usually because the various connections to ground in a system will have minute differences in resistance to ground. Minute is the key word here, so it seems like an answer to your OP question should acknowledge the idea.
Go for it one step at a time. It will probably work just fine and if not, you may have a clue as to what can be improved. For example, you can probably trace the ground wire into the chassis and replace it so that it has a little resistance as possible.
Don't bother trying to measure for the resistance... the contacts of a most VOM probes have more resistance than the amount that you would need to measure for.
Have fun with your record collection!
best regards,
mike