Wizzard,
The -10 / +4 settings on your sound card refers to the output level, + 4 dB being louder than - 10 dB. Which one you use has to do with what you're plugging the output of your soundcard into. Home stereo amps and audio gear is often times - 10 dB or even - 20 dB. Professional power amps and most prosumer mixers accommodate + 4 dB levels. A good rule of thumb is, if it has rca connectors its - 10 dB and if it has 1/4" or XLR connectors it's + 4 dB.
Recording levels are a different thing. When recording on a DAW it is important to leave enough headroom (room on the meter) to allow for any processing your planning on. If you add eq or compression many times it will add level to the signal. This is especially true if you are boosting rather than cutting regions of eq. It would be safe to record at levels of -10dB to -6dB on your digital meters. This should allow enough headroom for any additional processing. .......... Fats

Just an additional word or 2:

It's a very common thing to have digital masters totally maxed out on level. This is undesireable for a mastering situation. Back off just a little & you will have a more relaxed, unstressed sounding final product.

This is true whether you are going to CD or vinyl.

Don,
Good point. I find it interesting that at Abbey Road, EMI would have the engineers work in the mastering room before they would allow them to become what was termed a "Balance Engineer" i.e.; working the desk in recording sessions. This was to ensure that the engineer would have an understanding of what was required to make a good sounding master transfer to vinyl. I wonder if this was a common practice with American labels too? Now days of course it seems to work the other way with mastering engineers rising from the ranks of recording engineers. ....... Fats

thanks for the info.

Concerning PT MIX, I have to say that when you record too hot, using over 24 tracks, things start to sound very strange, even with no plugins or gain changes. I have noticed that recording at -6db is a good practice.

If you change your mind later, for example, adding Waves Q4/Q10 or C1, things will be much sweeter.

We always have to take care of RMS level.

ACB,
Alo! It sounds as if your computer is running out of horsepower at mix. Have you ever checked you CPU and disk usage meter? If your running at over 60% on the CPU your going to start hearing what I like to call "crunchies"... this is hard to trace down because the second you solo something you CPU usage drops! If this isn't the case perhaps what your hearing is the dreaded 2-bus problem that we have been hearing so much about recently on Forum. I suspect that Pro Tools 24 floating point processing may be a culprit in this scenario. ........ Fats