Help amp for Vandersteen 3A sig w/ Anthem pre 2L

At your budget point, I would suggest a McCormack amp. You could certainly squeeze a DNA 125 in there. They really do well with Vandersteen's. Vandersteen's are not as easy a drive as some suggest. The DNA series have the grunt.
One of the better amps and the one I used with the 3a Sigs is the Theta Dreadnaught I. Unfortunately, they only show up every blue moon.
Richard V. has backed off biamping the speaker but a biwire is a must. I used a 4 channel Dread and didn't think it sounded as good as just biwiring 2 channels of the amp.

I personally have had no experience with the Anthem pre so I'll reserve comment to someone else.
I can say that a tube preamp seems to balance out well with a SS amp with the Vandersteen's. I used an Audible Illusions pre for years with good success.

I didn't quite catch the ground thing either. Since I use the Dreadnaught, being balanced, I don't know how you would do this.
I know Vandersteen has more recently backed off biamping. This was in response to a few questions on his website blog.
Since neither wire (+ or -) is grounded in the Theta, I don't know anything that could be done.

Bob R, Go to the Vandersteen sight and read his question forum. What gives? Got me!