yjoh,
You and Jazzmammal asked "why" pros recommend recording at -12. Well here you go. Ethan is a well known pro -
"Folks who have used analog tape recorders but are new to digital recording tend to set the record levels too high. With open reel tape and cassettes, it's important to record as hot as possible to overcome tape hiss. But analog tape is more forgiving of high levels than digital systems. Analog tape distortion rises gradually as the signal level increases and becomes objectionable only when the level gets very high. Digital recorders, on the other hand, are extremely clean right up to the point of gross distortion. Therefore, I recommend aiming for an average record level around -12 dB. or even lower to reduce the chance of distortion ruining a good performance."

Source -
http://www.ethanwiner.com/mixer2daw.html

I do not work here, but the benefits are still awesome
Make your sound your own!