Before I go into this I'd like to say I have not heard the Vandies- So I only share my personal experience, and I suppose taste, with the 99's.
As an owner of the 99's I can say they are an amazing speaker and VERY versatile with the amps which can be used. We hooked both SS and tube amp up to them and to our surprise both sounded very good. Since the 99's are 99db efficient (hence the name) you do have to watch the gain with high watt SS. With 16 watt tube amps the speakers get plenty loud for my room.
The separate bass amp volume for each speaker is very effective and helpful as I listen with kids upstairs at night and simply tame down the THUMP. The bass is tight, full and seamless through the mid range. In fact to me the speaker as a whole is very balanced across the frequencies. They also have a built in rear firing tweeter which helps add to the sound stage and lifelike feel. The ambient tweeter is also adjustable with it's own controller as is the bass
If I could summarize their sound in one word I would use "alive."
As I said I have not heard the Vandies but for a perspective I have heard B&W 800 series so I will contrast with the 802. The 99's seem to give a more personal feel to the music space to me-it's the old analogy but one that fits "it's as if they are in the room." I think this is due to the front row/with the band sense I get from the 99's where as with the 802 I felt mid row back. The 802's are smoother and definitely more laid back with a "grander" feel to the sound.
The 99's to me are more fun. With the pop of the drums, the brass of the horns- The sax seems to vibrate me in the way a live sax can but with no fatigue. The guitar, piano, drum, all are in the room with appropriate dimensions for each instrument AND for the style of music being presented. With some speakers the song seems to have only one rhythm based off the drum or guitar. I think because the 99's are so dynamic I can both hear and feel multiple rhythms in the music which is why I just can't keep still when listening to these babies.
But make no mistake, "in the room" is not all this speaker can do. This is what I struggled with with other speakers. Hearing a "grand" speaker with classical is wonderful but hearing this same grand smooth sense with rock, acoustic, solo voice etc. becomes repetitive and tires me. I don't know how they do it but the 99's seem to work well with every style. Do a search on the 99's and you will see I am not the first to say this.
Listening to Cincinnati Orchestra via the 99's gave me the feel of the hall, the space, the black, the energy as well as the texture of the woodwinds, the vibration of the strings and the presence of the orchestra. I was appropriately placed back in the experience and it did feel both spacious grand and alive. With a switch of the CD I was intimately in a smokey hide away bar listening to Miles Davis. The 99's take me to different venues with every new album.
Anyway- enough eh? Just like to end to say that I am not a dealer and I don't mean to imply to any that the 800 series is not a great speaker also- just the 99's are more attune to my ears.
Best luck
