USB Mixer Stereo Inputs Help!?

[Arron]

Hi im looking at purchasing a mixer for my setup however ive never used a mixer before in my own studio and Im struggling to find something that works for me. All the mixers ive come across have loads of mono inputs for mics and only a few stereo inputs however my music is all done on sythesizers which need to be in stereo for their delay effects etc I believe stereo only mixers dont exist is there something im missing?

Thanks!!