Broken Kenwood 9600 Receiver and Broken Kef 107 Speakers

[DanApril1961]

After plugging in my Kenwood 9600 receiver that I have been
using for years to my recently purchased Kef 107 Series 2 speakers,
the speakers popped and and receiver stopped working.
The receiver lights up but now makes no sound with any speakers.
The speaker foam surround is completely deteriorated.

Questions
1. What would cause this to break the receiver?
2. What would be involved in repairing the receiver?
3. What would be involved in repairing the speakers?

Thanks for any help in advance.

 

[Pano]

Sounds like you got serious DC on the outputs of the Kenwood. That can fry the speakers.
Do you have a voltmeter to measure the Kenwood outputs? Disconnect the speakers first.