I have a VT and it does a decent job, however, I was in GC this weekend looking for a real tube pre/overdrive/distortion pedal and left with a Blackstar Ht Dual. At first I had no idea what this was or who Blackstar is, but now I do. Only $25.00 more than the VT, but considerably less than any DHA or EBS tube pre (and bring a can of soup for another 10% off). Pedals a little big, but runs off a true AC adapter which really allows the tube to burn! Compared to the VT if I'd found this first I would have never bought the VT - this is a "true tube" pre. This must be a very underrated/ underappreciated pedal because there's very little here at TB that describes or criticizes it.
Blackstar is a British Company...and only recently have they been widely available here in the U.S.
I tried their HT pedals and found them to be freakin' killer on guitar.....not so much on bass....quite a bit of low end loss overall...but if you can live with it or use something like a Dark Boost in conjunction with these pedals they would probably work great...