if you wanna improve the sound of you mixes for a budget of 1000 Euros, I recommend two options:
-
buy a really good headphone like the Beyerdynamic 1990 or a sennheiser 800s, where you can listen very closely to every nuance of your mix.
-
improve the acoustics of the room you mix in (if you havent done already). So you need to measure the frequency response of your room, place absorbers on the walls near the monitors and diffusors in the back. For equalizing room nodes, a dbx driverack pa2 might come in handy. But it can only equalize the frequencies for one sweet spot.
this should help you to listen and improve the sound of your mixes, so you can make better judgements.