If the ZERO is not loaded properly it will ring (adding harshness and obscuring detail) like any other inductive device. Ideally the speaker load should be 4,3 or 2 ohms, and if loaded that way the input will be 16 ohms. Other combinations are possible, but *in general* the ZERO is usually not be particularly helpful on a speaker that is already 6-8 ohms.
IMO you are far better off trying different speaker cables on the Merlins rather than ZEROs. If you had Magnaplanars it would be an entirely different story!
IMO you are far better off trying different speaker cables on the Merlins rather than ZEROs. If you had Magnaplanars it would be an entirely different story!