The LS-550 (New) proved to be a good mainstream 550 W unit, providing a decent efficiency between 84.5% and 85.7% if you pull between 20% and 60% (between 110 W and 330 W) from its labeled wattage. Delivering 80% from its labeled capacity (440 W) efficiency dropped to 82.7%, still a very decent number. At full load (550 W) efficiency dropped to 80.3%, still above the 80% mark.

Ripple and noise were always below the maximum allowed.

Compared to LS-450, even though they are based on the same project, all main components were upgraded on LS-550. This is really nice to see, because some manufacturers when releasing a power supply with a higher wattage only replaces the secondary rectifiers, not upgrading the primary.

A very important thing to keep in mind if you buy this unit: warranty. You have to register your power supply with BFG within 30 days of its purchase, otherwise you will only get a two-year warranty instead of the full five-year one. This is really tricky, as most users do not register their products with the manufacturer.

The only problem right now is finding this power supply for sale; it looks like it is on its final days.