This is a great three headed deck so you can actually listen to the recording at the same time you made it by switching from source to tape and compare... If there is a difference between source and tape you can minimize it by using the record EQ switch.
What you refer to as 'guages' are called VU meters or voltage unit meters. ANRS or Automatic Noise Reduction System is JVC's proprietary noise reduction circuitry. It seems to work best in reducing tape hiss on Type 1 or FeO2 tapes. ANRS is roughly analgous to Dolby B and Super ANRS is roughly analgous to Dolby C noise reduction. I have owned my JVC KD A-77 STEREO CASSETTE since 1980 when I bought it new. It's still working like a champ. Type 2 or CrO2 Super Avalyn tapes or Maxwell UR tapes or Sony UX High Bias tapes work very well in the JVC KD A-77. HAPPY CASSETTE RECORDING!
The Super ANRS is not analogous to the Dolby C noise reduction. It is the ancestor of the HX pro without signal variation in recording. Unlike the HX Pro it is fixed and does not vary the bias depending on the signal. It's Dolby B with downward compression in the high frequencies. The decoding applies a perfectly compatible upward decompression and restores highs impossible to obtain without HX Pro. It improves the treble of a Dolby B encoding. It is interesting to use it with commercial pre-recorded tapes, in particular old ones and those with azimuth errors. To test and challenge this, use a Type 1 tape and record a very high-pitched source with peaks above 0. They will play out with more energy than in Dolby B.
The "Super ANRS" WON'T sound any different unless the tape was recorded with Super ANRS turned on, and played back on a deck that has the ANRS subsystem. "I don't hear any difference, but some people do". SMH.