RMS meters for mastering ?

I read the K site and it's been really interesting, even if, I confess, I didn't understand everything (i'm french and an amateur, so some things appear a little dark to me). Do you think K-meter system is useless if I can't calibrate my system ? In fact, here is the real question I'm asking myself concerning all this : I want to understand my RMS "red-zone" problem, and what it means. I got an audio file that is always under 0db peak level. But it can go from +2.0 to +5.0db RMS on the default configured REAPER meter : - how is configured the reaper meter for RMS by default ? - is that a problem to go over 0db RMS ? If not, which value should I not go over ? - I know I can influence RMS meter value by EQ some frequencies (spotted with SPAN) or by playing with panning. Is there other ways to correct RMS loudness ? Because limiting seems to have a real low effect on RMS meter values in my case (but it reduces peak levels). - What is the benefit of calibration when using something like K system ? I mean, it surely can help "hearing" bad RMS behaviours. But will it be a guarantee that my mix will be well, "rms speaking", on other systems ? I'm trying to understand all this ...

Quite agree with you. Will try. But the friend whose composing the CD i'm working on wants it to be really loud. It's a very very talented and intelligent man, but even after I explained him the interest to not have a too hot CD, he told me "don't want it to sound like crap, but please make it the hottest possible withou having majour sound issues". So, it's not my CD, it's his, and I'll do it like he wants, as I'm no pro and I'm happy to work with him. By the way, thanks a lot for your answer, will help a lot :)

With my own band was the same story though. Really hard to explain that to people ... My bassist, who is a great friend and a real big head, told me when first hearing a mix I did "man, your screamo mix has no balls, it has less level than the post-rock CD i'm currently listening to". :(

the way around it is to master it both ways - squished, and normal - but then bring them both into one session and level match the squished one against the normal mix. then a/b them. you can always turn the softer mix up, and radio/broadcasting usually adds another 6db of compression anyway.

Can all of the tracks be configured to present levels in RMS? It appears that everything shows peak, except the master bus.

I hope no one minds but I'd like to piggy back on this thread and see if someone could see my thread/question about metering here: Basically,I'm getting different readings in the T-Racks shell (stand alone) to Reaper and figure it's probably because of one of these settings in Reaper for the metering.What settings should I be using/trusting?Sorry if it's really stupid or obvious,I'm just a bit confused.

RMS metering for us amateurs 

I use Schwa-Audiostatistic-plugin and let my mix stay at about -20db rms. The mastering goes up to about -15db rms (at schwa-audiostatistic-plugin). Great plugin as it shows you the dynamic range and other usefull things. I never use the rms-metering at the masterfader. It shows peaks and not level over the whole time.

Sides of Reaper's Master VU shows RMS B.T.W.