Audio Research VT100 MK11 vs VS110

I have listened to both, VS is a scale down version of thier VT series, less extension at both ends. VT version 1 and 2 are less stable and harder to bias and mantain then the VS though. VS is very user friendly and stable. I have not listened to the VT mark3. I bet that is the best sounding of them all.

I've listened to all the VT-100 series (Mk I, II & III). Without a doubt, to my ears, the Mk II is the best sounding of all three (and the one that I own). The MkII doubled the power supply of the MkI, plus, added an IEC power input, so you can use the power cord of your liking (very important in getting the most out of it). It has powerful bass (again, the power cord you choose will make a huge impact here...I use a FIM 'Gold' model power cord....GREAT with this amp) with an airy overall tonal presentation. The Mk II also has a wonderful stage presentation. Again, IMHO, the MkII is unquestionably the best of the three. Oh, if you get a VT100, use the balanced inputs, I think they sound better.
The VT100 MkI & MkII has an all tube input stage, where the Mk III went to a solid state input stage, and sounds like it. It does have a little better detailing, but lost the musicality of the MkI and II.
I'm not as familiar with the VS110 as I am with the VT100 (but I have listened to it). However, to me, the VS110, even though it is a newer model than the VT100, just didn't float my boat the way the VT100 did.