Tried the Coda/Continuum integrated with good results, also heard the MF A300 integrated in a showroom with different Vons, but wouldn't put them anywhere near to on par with the PS Audio digital amp and the PCA-2 preamp combo, which is pretty special.
I wouldn't try tubes with these speakers unless you have a tiny room and don't listen to dynamic or demanding music, but perhaps a hybrid integrated tube amp, with the tubes in the input stage, would be a excellent choice, of which there are many. But, again, I still feel that 100wpc is the bare minimum for controlling the woofer, and the more current the better. Current is usually where integrateds are lacking, saddly, and in turn bass control, which is a huge issue with speakers that can put out flat, fast and deep bass into the mid 20hz region, a feat which few speakers at any price can do, so this is an important challenge to address for VSA owners, at least if you music tastes demand it.
If you can give me an idea of what is your budget for the amp/pre/integrated and source are, and what your music tastes tend towards, I could make some other suggestions for specific gear, as I've tried countless dozen pieces with various VonS speakers, and have a pretty good idea of what they mate well with and what gears suits what types of music best. You're also welcome to contact me via email if you wish.