Tripecac

The suggestion to EQ each track using Quad Curve EQ in pro channel is a truly great one.

I don't think I would ever have the discipline to do this.  Due to time constraints (and habits), I work very, very quickly.  I do almost all my editing on the fly (during playback), stopping only occasionally.  Having to fiddle with an EQ effect on every single track would totally kill my flow, and probably my enjoyment and therefore motivation for making music.

 
This particular recommendation was for trying to achieve balance and clarity, and my recommendation included doing a one-time setup of a project template with the eq bands (gleaned from a commonly available chart) already preset, so you'd only have to do it once.  Honestly (and respectfully) it takes a lot less time trying to do something that will help once than to try a bunch of different simple fixes that don't actually fix anything. Why don't you just try it with a simple drum/guitar/bass scratch tune and see if it doesn't help? You'll be out maybe 10 minutes.
 

Tripecac
This would be an inconvenience, and I need to make music making as convenient as possible, or else it just won't happen. 

 
With the state of the art in DAW's and playback devices today, there really isn't a convenient way to produce a fine sounding mix that sounds good on just about any device you play it on. Someday we won't have to do any of this stuff, the software and hardware will figure it out on the fly and do it for us. Until then, we're stuck with the inconvenience of experimenting and iterative learning.
 

Tripecac
 Anyway, this why I was hoping for a quick software solution.  
 
 I haven't tried the reference mix solution.  It would be easy, since I have all my CDs on my computer.  What sort of song do you recommend I use as a reference?  I listen to a lot of 80s post-punk, most of which was cheaply recorded.  And recently I've been listening to lots of 60s music, again with less-than-perfect mixes.  Of newer music, I like the recent New Order album.  Would a song off that be a good reference track?

 
Pick one and try it. Just about anything produced professionally will sound better than anything I can do. That said, I tend to go for the musical genre and sound I'm trying to get close to. Just drag it onto a new track, mute your stuff, play it for a bit, then mute the reference, play your stuff, and so on. You'll quickly hear the differences.
 
I'm afraid that unless you're willing to experiment a little and learn what works for you, you're going to just have to get used to bass-heavy tracks.
 

Travis, what might be useful is an idea of what your projects consist of.
 
Do you record mainly midi, audio or a mixture?
What sort of track count is in an average project of yours?

Hi, these days I deal primarily with soft synths (Cakewalk and Native Instruments).  Very rarely do I add audio.
 
A typical project has 8-10 MIDI drums tracks fed into one virtual drum kit (usually a Kontakt or Battery kit), and then 6-10 tracks of other instruments, some of them sharing the same virtual instrument (e.g., separate MIDI tracks for left and right piano).  So maybe a total of 15-20 tracks of MIDI, and 5 or 6 soft synths.
 
Here are is an example of a song that sounds muffled when I playback on anything other than the HD 580s:
http://tripalot.com/tripecac/albums/motions/#growup  ("Growup")
 
Here is my most recent song, to which I added treble via an EQ on the master bus:
http://tripalot.com/tripecac/albums/motions/#so-tired-im-wired ("So Tired I'm Wired")

To my ears, the second song sounds noticeably crisper than the old one.

My idea was to apply the same master EQ technique to all the other songs on this album and see how it goes.  And then, if they all sound better (on every set of speakers/headphones I can find) then I can do the same for older albums.

Vastman
Go to sonarworks and pick up their headphone calibration system.  They have modeled a long list of headphones and their system works wonderfully on my KRK 8400's... you have many options, as you'll see once you arrive at their site

+1

I plugged both set of headphones into the Delta 44, and did a quick A/B comparison.  The difference was startling; the HD 580s (which I use only for music) sound very crisp, while the HD 590s (which I use for every day listening) sound very muffled.
 
So, I then applied treble-boosting EQ to the master track on all the songs on my album.  I listened before each mix down, and tweaked the EQ here and there, and sometimes even the hi-hat levels.  Hopefully this relatively crude "fix" will get the songs sounding crisper on other devices, but I won't know until I have time to listen on the main stereo.
 
So here is a question: Could the HD 590s be muffled because I listen to them all the time?  Do headphones lose their treble due to constant use?

Tripecac
 
Here are is an example of a song that sounds muffled when I playback on anything other than the HD 580s:
http://tripalot.com/tripecac/albums/motions/#growup  ("Growup")
 
Here is my most recent song, to which I added treble via an EQ on the master bus:
http://tripalot.com/tripecac/albums/motions/#so-tired-im-wired ("So Tired I'm Wired")

To my ears, the second song sounds noticeably crisper than the old one.

My idea was to apply the same master EQ technique to all the other songs on this album and see how it goes.  And then, if they all sound better (on every set of speakers/headphones I can find) then I can do the same for older albums.

Both songs sound equally balanced and crisp (in their own right) given that they are different instrumentation etc.
 
To say that a mastering technique (settings?) can/will be used for all songs on an album seems strange to me unless every song has the exact same instruments at the same level and EQ (which I highly doubt).
 
And then to say you'd apply that same mastering technique (settings?) to an ewntorely different album seems eve weirder (to me).
 
Mastering an album, as I understand it, is to correct and/or balance levels, EQ and compression etc. so that one song is not 12db lower than the other or the bass is too boomy compared to the next or previous song (assuming you are looking for a clean flow from song to song).

Tripecac
I plugged both set of headphones into the Delta 44, and did a quick A/B comparison.  The difference was startling; the HD 580s (which I use only for music) sound very crisp, while the HD 590s (which I use for every day listening) sound very muffled.
 
So, I then applied treble-boosting EQ to the master track on all the songs on my album.  I listened before each mix down, and tweaked the EQ here and there, and sometimes even the hi-hat levels.  Hopefully this relatively crude "fix" will get the songs sounding crisper on other devices, but I won't know until I have time to listen on the main stereo.
 
So here is a question: Could the HD 590s be muffled because I listen to them all the time?  Do headphones lose their treble due to constant use?

Both sound "right" on my system too.
 
Do you think you're getting bass heavy, or treble light?  I kicked my sub on for kicks.  Definitely bass heavy with a sub set to sound correct for a variety of commercial tunes - not that I mix with it on.
 
I do NOT hear muffled or anything lacking in the top end.  I DO hear good separation and balance across the freq spectrum.

As Kevinwal said
 

Tripecac

The suggestion to EQ each track using Quad Curve EQ in pro channel is a truly great one.

I don't think I would ever have the discipline to do this.  Due to time constraints (and habits), I work very, very quickly.  I do almost all my editing on the fly (during playback), stopping only occasionally.  Having to fiddle with an EQ effect on every single track would totally kill my flow, and probably my enjoyment and therefore motivation for making music.

This could pose a problem.  If this is your workflow, then you might be getting just what you are getting.  If you just want to make music, then you are already doing that.  If you want to have your mixes sound good then it might behoove you to change your workflow, at least after tracking.
 
I work on the fly too, when I track, and I try to get the best sound going in, but when I mix, I spend ten times more effort on getting the tracks to sit together well.  But that is me, and you will have to figure out what is best for you.
 
Jesse Q. Screed
 
Jesse

Both songs sound equally balanced and crisp (in their own right) given that they are different instrumentation etc.

 
Sorry, your listening test was a bit too late!  The mp3s on the site are the new, "remastered" versions which I uploaded this morning.  So you're not able to compare the old mixes to the new mixes.
 
What I mean by "remastered" is I simply added a treble-accentuating EQ to the master bus, without changing the other parts of the mix.  It's not sophisticated or "real" remastering by any means, but I didn't want to say "remixed" because that would imply I took the time to re-mix the individual tracks together again, which I didn't!
 

Both sound "right" on my system too.

 
By "both" do you mean both songs, or both sets of headphones (HD 580 and HD 590)?
 
If you mean the songs, then great, mission accomplished!  The older songs on the album all sounded very muffled (to me) until this morning.  Now they sound better.
 

I work on the fly too, when I track, and I try to get the best sound going in, but when I mix, I spend ten times more effort on getting the tracks to sit together well.

 
Mixing is my least favorite part of making a song, so I try to minimize it.  Someday, if I actually come up with a decent song, I'll try to polish it better.  But for now, I'm content to just crank out my little instrumental jams as quickly as my kids, work, and Steam library allow, which means minimizing mixing...  I enjoy listening to the tracks "as-is", and usually don't fret about unbalanced mixes, as long as the songs don't sound too muffled or distorted!
 
So in other words, I'm still at the crayon stage, and properly mastering (framing) a crayon song is a bit overkill! :)

Anderton
Use Beats headphones. Then you'll wonder why your mixes have so much treble 

Now that's funny.... I don't care who you are.