Recording from turntable ok, problems from CD

Hi, I’m new to the forum.
I’ve been using Audacity for about 3 months now to convert my LPs to FLAC files. I’m on Windows 7, the “tape out” RCA jacks of my stereo amp are connected to my PC via a Behringer USB sound card.
Everything is fine when I record vinyl albums using my Thorens turntable. I adjust levels, remove clicks and so on.
Just for curiosity I’ve tried to record from another source, i.e. the CD player connected to the stereo amp through the usual RCA analog inputs…
To my surprise, the record level behaves very oddly: there is a sort of peak level fixed at-3db; if i turn the record level up I can’t go beyond -3db anyway, if I turn it down things get worse and the maximum peak goes down to -6db.
The result is a record that looks very flat, without the usual peaks and valleys, as if compressed in its dynamic range by a limiter.
It’s not my habit to convert CDs to flacs with Audacity, I use EAC, but anyway this thing is driving me crazy.
I can’t understand.
Any idea or suggestion?
Thanks in advance.
Fausto

To my surprise, the record level behaves very oddly: there is a sort of peak level fixed at-3db; if i turn the record level up I can’t go beyond -3db anyway

The CD output may simply be lower than the record output. Even different records will have different levels and different CDs will have different levels, although most CD’s are normalized (maximized). Does you Behringer interface have recoding level control?

if I turn it down things get worse and the maximum peak goes down to -6db.

Digital recording levels are not critical and it’s common to leave about 6dB of headroom as insurance against [u]clipping[/u]. (Analog-to-digital converters clip at exactly 0dB.) Pros record even lower. Then you can boost digitally after recording.

The result is a record that looks very flat, without the usual peaks and valleys, as if compressed in its dynamic range by a limiter.

That would be odd but it’s possible to get analog clipping below 0dB.

It’s not my habit to convert CDs to flacs with Audacity, I use EAC, but anyway this thing is driving me crazy.

It is best to avoid the unnecessary digital-to-analog-to-digital conversion.