Can anyone recommend a good amp (for a small apt) for keyboard/guitar?

Thanks in advance...I play a Yamaha S90ES and sometimes a Danelectro guitar, it doesn't have to be loud. Also, this is embarrassing, but I can't figure it out--my rinky dink little amp makes a horrible buzz, perhaps because it is so close to the keyboard--but my space is so small I don't have any choice. Will a better amp not have that horrid buzz in a small room? Looking to spend 300-400...

buzz is either a bad cable, a problem with the amp, or something environmental like bad AC or shielding issues. so the answer to if the new amp will help is a kinda maybe i guess. does it buzz w/both the guitar and the keyboard equally? do you have a different cable you could try? can you plug into a different circuit in yer apartment? all of those will help troubleshoot a bit.

also what kind of amp do you have now?

Thanks JJJusten, I'll try a different cable, which I have been using for keyboard and guitar--it buzzed like this in my old similarly small apt. I'm embarrassed to say I have now the smallest cheapest Marshall