First, you should have none of your gain stages (software, system speakers) turned all the way up.
Second, it typically recommended that one set their actual mixing volume for 80-85dBSPL at the listening position.
Third, it's much easier to control volume from a single location (a single pot, a pair of faders, etc.) than to control each speaker individually from their own separate on-speaker volume controls (which it sounds like you may have.)
OK, with the above in mind, try this procedure:
1.) Start by turning your speakers themselves down so they are audible but won't blast you out of your chair.
2.) Then get a test tone or pink noise or just a very dense mix and run it through your software, with that playback tracks peaking at 0dBFS (no clipping). in the mix channels. Then if your software has a master out volume control with metering, set that so it matches the tracking volume (or rides just below it, if you want a little safety margin.)
3.) Determine if the master volume control on the software is differet from your master soundcard volume or not (e.g. does changing the software volume change the wave playback volume setting for your soundcard/audio interface as well?)
If they are linked, then you can just use you software master volume control as your actual main playback volume control.
If they are not linked, then leave the software master volume where it's at after #2 (make a note of that setting, so if it's accidentally changed, you know what to bring it back to.)
If your software has no master volume control (meaning that you have skipped #2), then your soundcard volume control will be you main playback volume control.
4.) Set your main playback volume control to about 3/4 volume, or until any available digital meters are just below 0dBFS. With the volume at that setting, turn your speaker amplifiers up in tandem until you get a istening level at your listening position of somewhere around 80-85dBSPL (no more than 85.) Note those amp volume positions and mark them so you can go back to them if accidentally bumped later on.
5.) Your monitoring chain should now be set. Use the main playback volume control as determined in step 3 as your actual volume control.
Epilog: This process is based on the idea that you don't have an external mixer in your playback chain, which it sounds like you don't based upon your description. If you do have one though, then use the CR/Monitor volume control on that as your main volume control.
HTH,
G.