Toolbox149, I have Elite 20PFI. Any filtering choke in series will produce voltage drops, very big with most of linear power supplies, that draw the current from the mains in narrow pulses of very high amplitude. Furman in addition to big choke in series added big capacitor, that stores energy to provide enough current for these current pulses. On the wall side it presents itself as resistive constant load.
The only difference I found is perhaps more "even" bass and cleaner TV picture. I also bought used. Furman Elite has non-sacrificial over/under voltage protection. I've noticed few times it switched off when room lights got momentarily brighter and once when they got dimmer. It reseted itself afterwards. In addition to Furman I added whole house surge protector by replacing 2x20A double breaker with surge protected breaker (Siemens).
The only difference I found is perhaps more "even" bass and cleaner TV picture. I also bought used. Furman Elite has non-sacrificial over/under voltage protection. I've noticed few times it switched off when room lights got momentarily brighter and once when they got dimmer. It reseted itself afterwards. In addition to Furman I added whole house surge protector by replacing 2x20A double breaker with surge protected breaker (Siemens).