BAT-VK31se or VK-50SE or LS17?

By LS17 I meant Audio Research LS17

The VK31SE is NEWER and better and cheaper than the 50SE.

I have the feeling the 31SE may be better, but I noticed that the 31SE only uses 4 tubes, while the 50SE uses 8.

I used a BAT CK 30SE with my Classe CA-400 into a pair of Maggie 3.6R. I had to run the BAT up to very high settings on the volume control in order to get SPL's in the 90 db range. Assuredly this was partly a function of the speakers, but when I purchased an Audio Note M3 pre-amp, with choke rectified outputs the problem went away.

i had both---the 31SE clearly preferred.