"I have a new Rogue sphinx, I don't recall the unit I demoed to be especially noisy but I do find my unit to have some noise despite other owners describing the model as 'dead quiet'."
It's a new unit. That's all that matters. Don't settle for less than a unit that is doing everything you expected. Rogue needs to make it right. You don't need to be buying devices to quiet it down. Transformer hum needs to be eliminated and noise through your speakers needs to be eliminated by Rogue or they need to replace your amp. This is my opinion of course. It's ultimately up to you.
It's a new unit. That's all that matters. Don't settle for less than a unit that is doing everything you expected. Rogue needs to make it right. You don't need to be buying devices to quiet it down. Transformer hum needs to be eliminated and noise through your speakers needs to be eliminated by Rogue or they need to replace your amp. This is my opinion of course. It's ultimately up to you.