Dude Ivey
Thats one of the problems. When i put a mix on my ipod and play it in my truck which has a really good system it doesnt sound at all as good as it does through the headphones that i now have. What sounds good through my headphone has major eq problems through my truck system. I seem to be going in circles tryin to mix and eq audio hoping its gonna sound good on a good sound system. of course when i play commercial released music in my truck it sounds great.
I feel your pain. It's a debacle that takes quite a bit of research and patience, the latter more than the former. I have an Acura TL '06 model car, and a Chevy Astrovan, both with very different sounding systems. However, I spend lots of time in them both, so my brain starts to simply "know" if something is weak or off about one of my masters. I do find myself burning CD-Rs to audition in each. Neither currently support an AUX input, so that's something to deal with, as well.
What you have to do is figure out what seems to really focus the most on what is wrong with your mix. For example, what is wrong with the mix in your truck? Kick drum too weak, vocals buried, lead guitar too ear-piercing? Find out what's the most wrong with your mix on each listening device (i.e. headphones, your truck, your ear-buds, etc.), then work on taming each one of those in your mix. There's nothing wrong with using speakers you know for reference.
Yamaha NS-10's are still widely used in many big studios, but they sound horrible. The thing is, they are used, mainly because if you can get a mix sounding good on those, you're doing something right, and the mix will likely sound good on nearly anything. Although that's an old-school method, it still applies largely today. It's all about "translation".
With that said, I highly recommend getting a great set of headphones like the ATH-M50's Sharke mentioned here, for example, and listen to everything you can. Grab a parametric EQ and have fun with it, but find what frequencies work for "their" mix vs. yours. Also, realize that the recording itself may not be good enough. That happens.
Now, If you want good masters, you really need a great audio-chain, clean power, Class A "True" amplifier, and some great speakers in a great room. For example, I use an Apogee S/PDIF DAC, XLR Star Quad cables, a Pass Labs X-350 power amp, Monster Power Voltage Stabilizer and Pro Power Center (both Signature models) and a set of Polk Audio 2.3TL speakers with SonicCraft Crossover film caps, mil-spec resistors, some updated coils, and Alpha-core speaker cables. The cost adds up, but your ears can hunt down and destroy bad things much faster. Point-being, you're not alone in the quest to get it right. It's not an easy thing to simply "get".
So, enjoy those truck speakers! They are valuable, too! Keep trying, and you'll get it!
Best of luck!!