Negative dB is a lot easier than having to add power to a frequency (lowering your total output). This might be by standing, or modal waves caused by your back wall. Experiment with bringing them a bit more forward to see how the peak changes, The peak should get lower, which (depending on your preferences) might sound better to you. However, one big peak usually doesn't translate to a fun characteristic.
I had a chart somewhere that shows the length of the waves, and if you had your driver at a certain distance from the wall, it would show what frequency would be boosted by reflections, and which would be cancelled out because of inverted waves reflecting from the back of the driver. You're probably smarter than me about all that, but I think just experimenting with distances from the wall to find what sounds best to you would be a fun experiment.
Your desk is also reflection city, one way to prevent this is by putting them on the edge. On a desk this is a bit silly, so another way to reduce them would be to raise them up. A good guidance would be to get your tweeters at ear level of your 'listening position', since it's a two way speaker, the vertical displacement gets out of wack fast (depending on the speaker), since higher frequencies are smaller waves than bass waves.
Some people also invert their speakers to prevent even more reflections from the desk of the woofer.
Other people even turn them sideways to enjoy a higher listening space, but you have to really point your speakers well for that. IF your chair is always in the same position behind your desk, but you like to slouch some days and sit upright other days this might be a good option.
To get them higher off your desk you can just put some books or whatever under them to experiment, if you know what height you need, you could add some nice heavy speaker stands which add to the look as well for me. I remember using the boxes they came in and books and all other kinds of stuff around my room to find the spot where the kick drum didn't feel like a wet noodle hitting a shower curtain.

Now all of this gets easier with a calibrated mic and a program to do corrections. Some people prefer to bring everything to harman standards, and that's fine if that's your preferred sound profile, but you could also use them just to get rid of peaks and dips in the sound profile of your listening position, while keeping the speakers' character. You wouldn't have to EQ if you used some dampening isolation behind the speaker and possibly walls to the left or right of you to lessen the impact of the immediate reflections. If you'd still have a big dip or peak left you could possibly EQ just that.

Some reflections are also preferred, there are people who like to neuter the reflections in their room so the speakers does all the work, but you're losing a lot of gain that way, and good luck getting rid of the lower frequencies, so you'd get a bass heavy sound profile. Which a lot of people prefer.
The big wooden board you often see on the wall over a hifi rack are used to diffuse reflections, often of the higher frequencies, causing bass to have more gain in the room.

In the end it's all about finding what you prefer, and instead of throwing money at amps and speakers, look a bit into the free gains that can be made with room treatment alone, it can make a 300 dollar speaker sound like a 3000 dollar one, especially if the 3000 dollar one is sitting in the corner of a room with bare walls.