It seems that only the Mk2 version (fan under the cooling tower and with very thick copper wiring) had the switch on the back:
An externally hosted image should be here but it was not working when we last tested it.
This thread is going on 8 years old, but thought I would provide some expertise on the Krell KSA-50mkii.
During the 90's I owned 3 of these all at different times. The back panel key was to convert the unit into a 100 watt mono. This was all factory installed and nothing was aftermarket. The units came with a 6 inch black wire (used only when in mono mode) that was nicely terminated with coper ends. This was used to short the black (common) rear of amp speaker outputs. Only the Red terminals were used to connect the speaker. The only issue is I am not sure if you are to use the right or left rca for input. For this answer you would need to call Krell service.
I had a real love hate relation with this amp, but I keep in mind I had 3 of these. I rolled thru quite a bit of gear in the 90's and early 2000's. Of all of the numerous Krell and other amps I never owned more than once with the exception of this amp. I do have to say the 3 units I owned all sounded as sweet as people claim. They were very uniform in soundstage, both width and depth. At lower volumes this amp had an amazing 3d presentation, it just made music float in the air and the hair on my neck stand. My Issues was that I changed speakers and changed to some very inefficient models that the 50 watts could not deliver on more complex material.
During the 90's I owned 3 of these all at different times. The back panel key was to convert the unit into a 100 watt mono. This was all factory installed and nothing was aftermarket. The units came with a 6 inch black wire (used only when in mono mode) that was nicely terminated with coper ends. This was used to short the black (common) rear of amp speaker outputs. Only the Red terminals were used to connect the speaker. The only issue is I am not sure if you are to use the right or left rca for input. For this answer you would need to call Krell service.
I had a real love hate relation with this amp, but I keep in mind I had 3 of these. I rolled thru quite a bit of gear in the 90's and early 2000's. Of all of the numerous Krell and other amps I never owned more than once with the exception of this amp. I do have to say the 3 units I owned all sounded as sweet as people claim. They were very uniform in soundstage, both width and depth. At lower volumes this amp had an amazing 3d presentation, it just made music float in the air and the hair on my neck stand. My Issues was that I changed speakers and changed to some very inefficient models that the 50 watts could not deliver on more complex material.
