The only time I heard the VR-4s in a dealer showroom, they were being powered by the Sonic Frontiers Power 2 amp (stereo amp, ~110W) and sounded amazing. Might be worth checking out.
I think I can be of more help in your choice of pre-amps as I've auditioned both the BAT VK-5i and VK-30. I went to the audition thinking I wanted a warm, liquid sounding pre-amp, which is the VK-5i, but ended up preferring the VK-30 with it's more neutral presentation (leans slightly to the warm side of neutral) with amazing dynamics and PRAT. They are both very musical and help the music sound involving, so can't go wrong with either one, just a matter of which sound you prefer. Oh, and if it matters, the VK-30 is also much quieter.
I think I can be of more help in your choice of pre-amps as I've auditioned both the BAT VK-5i and VK-30. I went to the audition thinking I wanted a warm, liquid sounding pre-amp, which is the VK-5i, but ended up preferring the VK-30 with it's more neutral presentation (leans slightly to the warm side of neutral) with amazing dynamics and PRAT. They are both very musical and help the music sound involving, so can't go wrong with either one, just a matter of which sound you prefer. Oh, and if it matters, the VK-30 is also much quieter.