Recommendations for a good power conditioner? Do I even need one?

Get a used Synergistic Research Master Coupler for a couple hundred bucks, or newer SR Blue, whatever, just don't go more than $500. Because you need $300 for Perfect Path Solutions Total Contact, which at only $300 will do more for your system than any power conditioner or power cord you can afford.

Before spending any money get the Oppo on a different circuit 
make sure the stereo circuits are all on a different leg of your power panel than large loads w motors
make sure panel connects and grounds are clean and tight ( quality electricians maybe needed ) replace old worn 15 and 20 A breakers as needed. IF you have wall warts or a PC get them away from analog
:-) try that first....

also all the trash producers ( switchpower supplies, clocks, DAC’s) into a $500 Furman on mentioned dedicated circuit will do wonders

Add 1 or 2 iFi AC iPurifier for 100usd each for starters. Best value I know of.