To me what you're describing sounds normal. It's hard to know what exactly you're hearing "buzz" wise, but if the original amp has it, the model does too.
One thing I like to make sure people know about, most of the amp models have some interesting parameters meant to simulate these sounds. For example, the "hum" parameter recreates the actual hum of an amp. I'd make sure you've toyed around with the hum, bias, bias x, sag, drive, and other settings on each amp to see how they react to see if it's related to the buzz you're hearing.
Also, keep in mind that the Helix has a built in noise gate which you can activate to reduce a bunch of additional fuzziness - useful in the same way a traditional noise gate is useful.