Your Anthem A2 is spec'd at 29db gain, with input sensitivity of 1.5v. The Grounded Grid preamp is spec'd at 12db gain, so you have a combined preamp/amp gain of 41db -- if anything, a bit on the high side. And the von Schweikert VR3 are 87db/w/m efficient. The only way you can have a problem is if your source has unusually low output (considerabily lower than the normal 2V out on CD players), or if there is a gain constriction in either your preamp or the input stage of your power amp, or your power amp output stage is not fully functioning, or there is something unusually wrong in the speaker crossover dramatically sucking power. Or the preamp has an unusually shallow taper. You're not lacking gain -- if anything you have surplus gain to scrub off.
Phil
Phil