Seems to me that it would depend on what the needs are. Voltage regulation, DC blockage, filtering of RFI and/or EMI. Conditioners differ in there ability to affect these different issues. There are conditioners, voltage regenerators, and filters. Some use a combination of these. I have no experience with any of the aforementioned devices.
At the moment I plug my Pass XA25 amplifier direct to a dedicated line. My Aric Audio Pre is on a second dedicated line. My digital equipment is on a third separate dedicated line run through a Emotiva CMX2 into a PS Audio Ultimate outlet (a balun transformer). Outlet ->PS UO->CMX2 -> equipment.
At the moment I plug my Pass XA25 amplifier direct to a dedicated line. My Aric Audio Pre is on a second dedicated line. My digital equipment is on a third separate dedicated line run through a Emotiva CMX2 into a PS Audio Ultimate outlet (a balun transformer). Outlet ->PS UO->CMX2 -> equipment.