Every conversion loses something. The original shows from the '60's were CRAP by today's standards. They got converted to digital for broadcast. Then your converter turned them back into analog. Then your DVDR converted them back to digital and recorded them, likely with compression. Depending on how your player works, they may get converted back to analog again.
All my stuff is recorded in .wtv format by media center. There are multiple audio channels. When I play them back with VLC, the default audio channel varies by the TV channel, network, show or randomly. Changing the audio channel does affect how it sounds in some non-deterministic way. On some PBS recordings, the default audio channel deletes the dialog, but plays everything else. Other audio channel has everything. I had to write a program to let me change audio channels without a keyboard.
I don't know how the Philips device works. There may be some equalizer configuration that can compensate for frequency selective issues.
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