Don't get me wrong, I really like the nostalgia of vintage stereo equipment, but I think you are going about this wrong.
The amp section in your sr6200 is much more robust. You should be using it to drive your speakers.
Frankly, there is no need for the 1070 in your system, but if you want to incorporate it then hook your speakers back up to the sr6200 and run RCA cables from one of the Tape Out jacks on the 1070 to any line level input on the sr6200. Your 1070 will then function as a pre-amp and you can run sources into the 1070 or use its tuner and pass that signal on to the sr6200.
Again, there is really no need for the extra complication caused by adding the 1070, but the way you are running it now makes even less sense to me. If you had a turntable then I would set it up as I advise and connect the turntable to the 1070 as the sr6200 does not appear to have a phono input (at least from my quick goolge image search of the back panel).