Help request: MA6100 speaker switch and pre out questions

[Martin Angus]

I recently picked up a nice condition MA 6100 integrated amp that now works well with the following exceptions:
1. Front panel Speaker selector buttons seem to be bypassed as speakers work whether buttons are in our out. Status lights operate as they should - on/out, off/in. Even with the lights off the speakers are engaged.
2. The strap that connects the center terminal from the "pre out" to "amp in" has no effect. Unit works without the connector in place.

Are these two issues likely mods someone has done in the past or is something defective? Ideas what I should look for?

Thanks in advance

 

[c_dk]

Sounds like someone made some " upgrades?".

 

[Martin Angus]

Mystery solved...Someone shorted the speaker switch terminals and the pre-power jacks internally. Snip, snip...problem solved, though I am very curious as to why someone might go to that trouble to handicap an amp.