Using what I said and the car, If you've had the same car for a few years and have been listening to hundereds of albums and at different volume levels, you have learned what it sounds like now. So then you pop in your own creation and and should be able to compare what you hear. 
 
Like I said, I don't care how much you fuss and spend. it's all about learning to listen to any given system. Of course the better the system the easier this is to achieve. 

I read these comments and see myself right back where you guys are now. What sucks is, though I love to help out and give advice, I can't even give any here other than I never mixed anything worth anything on headphones. I have tried so many.....it's crazy. I know cans are the only option for some of you. The only advice I can give is to try a few and sell them if they don't do what you hope they will do.
 
What sucks even more is how some of these cans change over time. I've been an AKG K240 DF supporter for a long time. I've cooked all of mine over the years and had to search for something that would help me. I hated searching for them as much as trying every pack of guitar strings and every guitar pick up I could find.
 
I bought a set of Sennheiser HD's based on a recommendation. Though they are semi cool, they are quite bass heavy for my ears. Yet bitflipper has the same pair and claims his lack a little bass. I tried the AKG studio (gold ones...really nice) and they fell short. I tried the M50's, AKG pro's....uggh! I finally went with the AKG K240MKII's which are sweet and almost sound like my monitors.
 
That said, nothing in the "headphone" software area has done anything for me. I've tried them without any success. Luckily for me, ARC has worked so well along with having a sub, what I mix sounds the same everywhere. All my vehicles, headphones, ear buds etc. The only place I can say my stuff fails is on some lap tops. I think I've obtained a happy medium as far as getting things to sound acceptable on everything.
 
I don't listen to music on ear buds or cans. I understand that just about everyone else does. I do the majority of my listening in my vehicles and in my studio. So that's where I tend to make my decisions. Whether that is right or wrong, it's what I feel is best and it works for me. I really don't care if my music may lack a little low end in certain headphones or earbuds. Most devices these days offer onboard eq. I'd rather people acclimate to what I'm doing as it is much easier for an individual to alter something for THEIR ears than it is for ME to try and keep the world happy.
 
Remember this little tidbit of information. You can never go wrong if you just add enough bass to round off your mix. As soon as you feel the bass, chances are you're using too much. With that in mind, you'll just about never ruin a mix with mud and clutter. This is where the home recording guy is failing. Stop trying to over-master things and shoot for neutral. Leave the super loud and sub low stuff to people that know how to handle that. Honest when I tell you, things will change for the better for you if you try the above.
 
I do quite a bit of work for important people in this industry. If you heard what a REAL mix sounded like BEFORE mastering, you would never load up on sub low bass again. Trust me....round out the stuff to where you can hear some bass with a subtle bass push to lightly feel it. Anything more than that and you'll lose 75% of the time especially if you do not have the right room, monitors, correction or experience.
 
Control the bass, watch piercing high end and don't buy into the "digital = harsh" myth while trying to warm everything up with excessive mid range congestion. Happy medium.....nice and neutral. Let the people that are listening to your music ruin it with their excessive EQ's. The more neutral you are...the better it will sound once they attempt to eq the heck out of it. LOL! :)
 
Got a good mix in cans....send it to someone you respect the opinion of so they can tell you what they hear. Like Leadfoot said....after years on the same gear, you just get a handle on what sounds like what. Learn what you have if you have no other alternative. It really can help you to send some stuff to someone that is credible enough to tell you the right stuff. That said, keep telling yourselves.....you shouldn't really have to LEARN a room or a piece of gear.
 
Meaning.....when everything is just right in your room and with your monitor environment, mixing is just about NEVER a guessing game nor is it a "learn your room" type of experience. It's actually a lot more simplistic than people make it. You hear what you hear, and you know what to do. Simple....as it should be when all the pieces are in place. I'm mixing the core of a song from scratch in about 2 hours. 9 times out of 10, what I come up with sticks with little to subtle alterations.
 
When it is a guessing game or a "learn the room" situation...it's because you're limited or stuck with what you're stuck with. I mixed on monitors for years and failed because I didn't have the right stuff or at the least, flat monitors. This forced me to do the majority of my mixes on cans. Well, they were fair at best but nothing to brag about. The day I fixed my room and dialed in my monitors was the day the black clouds parted and left for good.
 
In a nutshell.....what I'm trying to say is....don't stress out with getting a major label mix if all you have are limited resources and headphones. Do your best, enjoy what you're doing, don't stress out and don't over-think anything. Sure, everyone wants to have good production.....but I've heard only a handful of people that were able to excite me with their headphone mixes.
 
Not that my opinion means anything....I'm just saying, try as you may, you'll *most likely* never get to that "wow" level as long as cans are your only means. So just do your best and keep putting out music without stressing or trying to take over the world with production. :) This is meant to pump you up and keep you from stagnating, not deter anyone away from getting better.
 
At the end of the day, I'd rather have a few albums worth of material out there to show people what I can do over having 3 songs that took 10 years to sound good. Put them songs out there and don't look back. If you get a record deal or decide to use another engineer or mastering guy etc...then worry about it. :)
-Danny