Using Low Pass filters is a good start, you can specify the cut off point to edge out hi frequencies. 'Warmth' in a musical sense is a quite subjective but If all your synth sounds are coming from within the box, you can stick an EQ on all of them and set it to a Low Pass filter. if you need more 'air' you can then boost INTO that filter but the cut off point will act as a 'barrier' from nasty hi end harmonics getting through and those, once accumulated, interfere with a lot of things. So round things off with filters, use a spectrum analyzer to see where your parts naturally roll off and adjust accordingly.
Across your 2buss, you can also apply a filter - a low pass and set it to something like 16 or 17k at 6 or 12db per 8ve. You can experiment with this but I can't hear above that so I'm happy about there personally. And then any 2buss eq you have you can use a bell curve INTO that filter to get air if need be.
Thanks Dude! great hints! =D worked good...
Someone knows or recommend eqs, compressors and pre amp plugins that can give a color just by sending the sound thru them? i bet there are some, that just by passing the sound thru will give color... someone?