I use DAWs to make backing tracks for live use with a number of vst's and sometimes recorded audio. They each start out as a custom written midi or a midi downloaded from the web. One of the biggest problems is getting them to the same consistent apparent volume level - not talking about peaks here I want the track to have a wide dynamic range but a consistent volume level. So a kick drum should be consistent in volume from song to song (except where there is a deliberate dynamic difference) At the moment I use a freeware tool called mp3gain to make tracks the same volume but I'd love to be able to do it all inside the DAW and remove an extra process step. Can X1 do this ? How are other people doing it ?

You will want to keep your RMS levels at the same level from song to song. You will need some compression to control the peaks. But if the RMS levels are the same you will have the same apparent loudness across the songs. Yes this can be done in Sonar.

Ok so how would you do it ? Can you please elaborate

Be sure you have your playback meters set to RMS and peak in X1. Thats the way I like them for play back. For record I only use peak. RMS doesn't matter in recording. The reason to both RMS and peak is so you see quickly what track needs attention in controlling level.

Adjust the the volume of your tracks and the your master buss so that the level falls into a range that is the same from song to song. Its really that simple. You will want to add a compressor on the master buss to handle peaks. You mentioned that you want some dynamics so that is the approach I would use. Don't be too heavy handed using the compression.

one of many threads on this site on how to setup a compressor
http://forum.cakewalk.com/fb.ashx?m=2116921

There are so many ways to make a backing track in Sonar, it all depends how you made the backing track. Do you have two tracks or a track for each instrument? Elaborating on how to do what you want is just too huge for a quick explanation.
Compression
Limiting
Volume Envelopes
The volume slider

He isn't talking about "backing tracks" but entire songs that are used in live performance.

  Exactly. I play in a duo and we use backing tracks from a laptop. Want I want is to 1. Get free/commercial/self written midi files 2. Load vsti's (and optionally record real guitar) 3. Record the song to an mp3 at a consistent level That way as we go from song to song I don't have to adjust the gain for each song live. I just don't know the best way of doing this and I'm hoping X1 can do it easily and that someone could explain how they do it

1. Get Voxengo SPAN (it's free)

2. Set it up for K-12 metering

3. Adjust your limiter gain until the meter is bouncing around 0db (plus or minus 4db, but 0db on average)

4. Repeat for all your projects

This will get them all pretty durn close to one another, assuming you haven't done anything wacky like cranking your bass drum to 11 on just one song.

The RMS levelling plus peak compression is good advice.  However, if you have compression available in your live hardware rig, I would recommend leaving the peak compression until the live performance.  That way you will not have a well leveled and compressed backing track next to an uncompressed set of live vocals and instruments.  By adding some peak (and overall ) compression on the performance audio, you can 'glue' the recorded and live parts together.

Cheers

Grif