A quick fix that could help right away would be to add an exciter to your master chain. I use the aphex exciter from waves, but i've also used the harmonic exciter from ozone, and the spl vitalizer (all work very well) Be careful, a little goes a long way and it's very easy to thin your track out or make it too harsh, so be mindful of that. Also, some stereo widening on 5k+ would really open up the top end, also used sparingly. Like i said these are two quick fixes that I use on my master chain to establish crispyness. Whats really important though is that each of your individual tracks sound proper pre-mastering.

-K

There is now some really good plugins that create that analogue sounding high end boost. The UAD Pulteq EQ (new version) really does the job, or Manley Massive Passive.
Also love the flux epure 3 - it just sounds expensive. I am sure there is some more good plugins out there.

...it's better to boost individual channels.  Exciters are also helpful but be careful not to overdo it.

Yes!! Be very careful with exciters and all that stuff on the master, because it will affect your whole mix that you already put a lot of work into! Just pick a few channels that already have some high end (I tend to not push my vocals too much in terms of highs as I find this unnatural and ear fatiguing...). I'd say the mix lives by contrast, so make sure to vary between bright sounding elements and darker sounding ones.

Artless Venture ♢