Recording meter blue bar never goes beyond -6 dB

I am recording vinyl records.
I am trying to set the recording level to avoid clipping (aiming for -6 dB). Documentation says the blue bar in the Recording meter indicates maximum level reached, so I play tracks (without recording) and activate the meter, after having reset the blue bar by left-clicking on the meter. I am controlling the source level through my pre-amplifier and through the “Recording” panel in pavucontrol.

The recording meter seems to work correctly, except the levels shown never go beyond -6 dB (idem for the blue bar), even if I boost the source volume to a point where the sound is obviously distorted.

Am I misreading the documentation, or is there another way to play a sample and find out whether the source sound level is ok, by obtaining the maximum level that was reached?

Audacity 2.2.1
Alsa / PulseAudio
Archlinux 4.14.13-1-ARCH #1 SMP PREEMPT x86_64 GNU/Linux

I found a workaround, which is to disable pulseaudio temporarily.
Start Audacity with:

$ pasuspender -- audacity

In Preferences, host is Alsa; set playback and recording device to the appropriate device, in my case it was

HDA intel PCH: ALC892 Analog (hw0,0)


HDA intel PCH: ALC892 Analog (hw0,0): Line: 0

respectively (integrated sound on the motherboard, input plugged into line in).

So it is probably an issue with Audacity and PulseAudio.