BAT VK-52se compared to Bat VK-51se?

I have done as many Google searches as possible and have found very little info to compare the 51se and 52se. I read the one review online I could find about the 52se and have heard the preamp in my system. I have never been able to listen to the 51se to help decide if it would be a worthy alternative. Any descriptions of differences in sound would be appreciated.
Not sure if you have read this one or not.