-6dB limiting on tape dub?

Total Audacity beginner here…
Windows, 2.1.0…
Trying to digitize some old cassette tapes,
and have tape deck coming thru a receiver so I can control volume going into laptop mic/line in.
I see RECOMMENDATIONS of keeping input level below -6dB,
but what appears to be happening on my test recordings is that,
if I don’t keep it TOTALLY below -6dB,
the blue Max Level (?) bars on the Recording Level meter will peg there
and not allow ANYTHING above there,
resulting in clipping of the peaks.
Is this a SETTING of -6dB somewhere?
Do I just need to suck it up and keep everything below that level?
I guess trying to keep levels “up” might be as stone-age analog habit that I need to get over.
Oh, and, since my first test recording or two,
the levels of the recordings have gotten stuck in the range between .5 and -.5,
where the first ones were from 1.0 to -1.0.
Not sure what’s going on with THAT and whether this is related to the first mystification above.
Any info, help or perspective appreciated!

so I can control volume going into laptop mic/line in.

Sometimes the analog microphone circuit on a laptop (or regular soundcard) can clip below 0dB. Overall, mic inputs tend to be poor quality, they are often mono, and it’s a “bad match” for your line-level signal.

The analog-to-digital converter should clip at 0dB (1.0 or 100%) but if the analog signal gets clipped first, you may never get there…

Ideally, you should be using a line input (but most laptops don’t have line-in). You can get a USB audio interface with line inputs, and you’ll probably get better quality using line-in. The [u]Behringer UCA202[/u] is an affordable option.