Hey it was the Mark Levinson that Audio magazine actually used to weld with. Shot 1 khz through it at max power and welded two pieces of steel together. An ML 3 I believe.
Here is a pdf of the sidebar to the review:
And a link for the issue it appeared in:
An enthusiastic reviewer might call a beefy amplifier an "arc welder" as an exaggerated compliment to its ruggedness and current -handling capacity. However, no one would really expect an amplifier to actually melt steel. Almost no one, that is, except this reviewing team. We say this amplifier is an arc welder and back up this statement with a photograph (Fig. B1) of two 0.05 -inch steel plates welded together by a pair of Mark Levinson No. 20s.
77.6 KB Views: 62