I've been using this plugin  http://www.hornetplugins.com/plugins/hornet-vu-meter/ to level the input signals on tracks. It's great for gain staging (so nothing clips in the Pro-channel) and you can color code it to match the tracks in Sonar. I set it to a -18 reference and used the autogain feature to level at 0VU. Works great! I did this screen capture while the song was playing so the meter is jumping around, but it will raise or lower the level to 0 with a click.
 

Follow up...after saving the autogain turns off, but your settings are saved. The VU meter has 12 colors to choose from so you have to pick colors in the VU and Sonar that match. My previous post may have made it sound like the color options are sinked...they are not.

Yes unfortunately there is no way to make the colors sync since no host reports this kind of information to the plugin :) but i thought it was a fair compromise. If you always record some kind of music you can make a project template with the plugs in and already colored tracks to so save even more time!
 
Saverio
hornetplugins.com 

so it can level the track, too? sounds like a great vst, I will check this out! 

Clint, What a great plug. Thanks for the heads up. Tom, not exactly, go here:http://www.hornetplugins.com/plugins/hornet-vu-meter/ and be sure to read the referenced Gear Slutz link.
 
Rocky  

Very interesting...I may have to get this one.

I have the old v1 w/o autogain on bu somewhere.
Do you know if there's an upgrade path available? I can't find any user account info in my software db.
I wouldn't use autogain on most tracks but I'd like to see how well it works.

I'm going to wait until it's $4.99
 
Joking apart - looks very cool - I'm going to check this one out. Thanks Clint

Got the upgrade to v2 for $2.75

It's best for setting the input level before recording. In my screenshot, the 5 tracks were pre-recorded. It is a simple little thing I was going to mix. I used the VU to set all 5 tracks to peak at 0VU before the mix. So it's basically a RMS level maintaining headroom. The Gearslutz article bluzdog referred to can explain it better than me. It also helps to level mixes before mastering. I was using 5 different meters yesterday for that and in the end you still have to use your ears, but it gets you in the ballpark. Great plugin...Thanks Saverio !