Downloaded Music

I use a (free) program called MP3Gain....not perfect, but pretty good

Cheers
Glenn

Change settings for burning a CD in Windows Media Player
There are a number of settings you can customize to make burning in Windows Media Player work better for you.

Click the arrow below the Burn tab, and then click More Options.

Make one or more of the following changes:

Burn speed. It is not usually necessary to adjust the burn speed unless you are having problems burning; in that case reducing the burn speed might correct the problem. This setting applies to all burners that you use with your computer.

Automatically eject the disc after burning. Select this check box if you want CDs to be ejected automatically after they are burned.

Apply volume leveling across tracks on the CD. If you are burning songs that were originally recorded at different volume levels, select this check box to minimize the volume differences between the songs on audio CDs that you burn. Doing so helps you to avoid having to adjust the volume as you play the CD.

this is another reason why i like this forum--the diversity

Bear in mind, whatever you do you can't increase the quality of a low quality recording. You can't "put the bits back".
Yes you can adjust the levels as Doug says but this won't change the quality (bit rate) of the originals.

I use Musicmatch and it has a facility for volume leveling

You need to perform a function on the MP3s called Normalize. This will convert the volume to a level you set for all the songs. A program such as MP3 doctor can help. Asuming of course all the songs are legally owned.

Cheers