Are you using IEM’s or wedges?
When you say it’s a bit harsh do you mean in IEM’s, Wedges or FOH?
If it’s IEM’s then you should easily be able to EQ your mix. If it’s FOH then your sound Engineer should be handling that. If it’s wedges then it may be the wedges you are using but should still be something that could be fixed with EQing.
^^^ Thirding this.
1- This should be handled at playback, not at your DI send. If it's on-stage monitors or FOH, the sound engineer will have to EQ some of that harshness out for you. If you have IEMs, everyone should be able to have their own mix, and ideally you should be able to EQ the harsh frequencies lower until it sounds less harsh. Which segues into:
2- This should be handled with EQ, not a filter. Filters completely filter out signal. They start rolling off approximately at the cutoff frequency, and rather quickly lower the level of frequencies to the point where they're functionally gone. But those frequencies, even the harsh ones still have sonic information and musical value. Just because they're harsh doesn't mean those frequencies need to be removed completely. It just means there's too much of them, or the harmonics are stacking in an unpleasant way compared to the rest of the signal. All that needs to be done is those frequencies need to be lowered a bit until they're no longer harsh. Whether it be a tight-Q band at a certain frequency, a wide-Q band across a frequency range, or a high-shelf across most of the highs and high-mids, EQ adjustment would be better than ruthlessly filtering out all the high end info until you tame the harshness.
3- An effect AFTER your DI's output would require a different type of gear. Pedals are expecting Unbalanced Instrument Level inputs. Your DI is either outputting Balanced Mic Level or Balanced Line Level (depending on the box.) But even if you had a processor set up for the correct input level type, after the DI wouldn't be the proper place to use it.
4- Even though the "proper" place to deal with this is the EQ on the playback (IEM mix, wedge mix, mixing board channel, etc.), i realize not every venue's PA is robust enough to actually deal with the issue. You could potentially handle it by getting an EQ pedal BEFORE your DI.
You could get an EQ with similar layout as your Amp's EQ. (Same number of bands; similar center-frequencies.) Adjust your EQ pedal using only negative EQ so that the harshness out of the DI is tamed. Then EQ your amp the opposite of your pedal to bring back up the frequencies you reduced on the pedal. It's not an ideal thing to do, but also, live sound is never ideal. It's always making the best of a compromised situation.
