See if you can find a production date somewhere on them and then i'll see what i can find out about them for you. Sean
Here's what i could find out about these pieces. Hope this helps you in some way.
M-L10 was rated at 160 wpc @ 8 ohms with no specs given for 4 ohm loads. Power Bandwidth ( which is different from frequency response ) was rated at 20 Hz to 20 Khz at .002% THD and .002 IMD. It used what JVC called "Super A" mode of operation and required 1 volt of input for rated power output. As you know, it has meters on it to measure power output and weighs in at 61.6 lbs ( to be specific ). List price was $2100 in 1983.
As to the P-L10, the line level sensitivity was listed as being 150 millivolts for rated output. 2 tone controls per channel with a moving coil phono input. Weight was listed as 26.4 ( boy, they sure were "picky" about exact weights ) and listed at $1650 in 1983.
Other than that, i can't tell you any more about them. Hope you enjoy them and get plenty of hours on them. Sean