The VT100 offers balanced inputs, for one thing. It's also just a better-sounding amp across the board. Still, the VS110 -- and the VS55, for that matter -- are mighty good amplifiers. I've owned the VS110 and still own a VT100MKIII. I've heard the VS55 several times, and it's one of the best tube amps for the money. Unless you need more power or just want to spend more money, the VS55 is the way to go, assuming you like ARC.