If it already sounds dull, chorus or reverb won't help. It'll just smear it more. Try removing the effects, if possible, and then adding slowly on each track...if it's even needed.
Have you got good pan positions for similar-range instruments to help keep them out of each others' way? Two guitars? One left, one right. Is everything except, possibly, the kick drum, snare, bass guitar and lead vocal panned away from center? You got left and right cymbals and toms, etc?
Are you sure it isn't a case of too little treble, but too much something else, like mids or bass that overpowers the highs? Instead of boosting high EQ to generate distortion, maybe lower something else, or narrow the frequencies of some instruments so they don't fight so much?
Are you cramming too much into the stereo master channel by feeding it too many too-high level tracks?
Leave everything where it is, and disable any effects. Put on some headphones and check and play around with pan positions. When everything is panned better, roughly, start playing with individual track levels, listening on monitors. When those get closer, you MAY have to mess around a bit with EQ on individual tracks. Try not to boost too much on anything. If they've been recorded properly to begin with, you shouldn't need to boost much of anything, and may just need to lower the high or low end of something to fit in and get it out of the way. Or, you may have to carve the middle of one guitar, and the high and/or low a bit on the other to get them to fit together. Just because that Les Paul through that Marshall sounds killer while you are standing if front of it cranked, doesn't mean it was recorded properly and will sound killer in the midst of a mix.
When you have a rough mix, start adding "desired" effects. Don't add effects just because you have effects. Have them if you want or need them to convey a message for that particular instrument, or want to set that guitar a bit farther back from the front of, say, stage right, as with a reverb. Once you start adding effects, the levels will possibly start changing, and their relationship to the other instruments will change. Tweak on. Too much effects, especially time-based ones like reverb and chorus, will smear attacks, soften highs, and create more low or mid mush. Think about it. You're taking an initial attack and applying very short delays with very quick, extended repeats. Instead of an initial reverb straight off an instrument, maybe a very slight delay, with reverb following that, mixed back in there? That could keep the attack and main signal clean and solid, and then introduce the reverb behind it.
That's what I would try. Sometimes it's not too little of one thing, it's too much of something else, or too many things in each others' way. There's also the dangers of two other things:
"I wanna hear my instrument" and "wanting EVERYTHING to be heard clearly ALL the time".
People want their vocal, or guitar, or bass, or...whatever to stand out. They played it. They think it should be the prime focus. That doesn't serve the song. Put your ego aside, and make your part(s) work with everything else. You can't have EVERYTHING be the prime focus, unless you are doing something like a solo acoustic performance, and neither can anyone else.
The more tracks you have, the more decisions you have to make as to what's going be sacrificed somewhat. Some things may just have to be relegated to a lesser role, but a role that is still important. Without it, even though it's back in there a bit more, the song wouldn't sound right. If it's brought forward, it causes an imbalance, and the song doesn't sound right. Find out what instruments need to be front and center, which needs to play a strong supporting role, and which ones are the extras that the scene would miss if they weren't there. Maybe you have an acoustic guitar doubling the electric rhythm a'la Pete Townsend? You don't need the full spectrum of frequencies from that acoustic. You just need the attack and a narrower range of frequencies...no booming lower end and blossoming mids. Maybe just the high and low-mid attack to cradle the electric.
Anyway, if you are trying to get EVERYTHING out front, what you'll likely end up doing is chasing your tail. "Wow...I just turned THIS up, NOW, I can't hear THAT. I'll turn THAT up...aaauuurrgghhh...now something else got buried!" By the time you do that a few rounds, you have everything maxed out and at least as bad as when you started.
Lastly, using compression can make a track punchy and clear...or it can kill it. If you compress every track to death, and then compress the entire mixdown...you're liable to have no clear high-end attack and "air" around the mix. Be careful with compression. Just because you have all that stuff, doesn't mean you always have to use it on everything all the time. Use it when it's needed. How do you know? Practice.
You have to make decisions, and experiment. You may have to do some of the above all combined...like panning and levels, as you go. Try some of this, and let us know if anything helps?