Tube Preamplifier for Krell KSA200S

I want to upgrade and replace my Krell KRC2 preamplifier.
I want to go to tubes.
Speakers are Sonus faber Electa Amator II.
I need preamplifier with balanced input and output.
Some options are:
Sonic Frontiers Line 2 or Line 2 SE
Bat VK30SE or 31SE
Other suggest would be accept.
Audio Research may be good. There are varying amounts of tubeyness in different tube pre's. The ARC's are more accurate but some people find them not tubey enough. Personally I think it's just right.
Of the options you've listed, the BAT 31 SE would be superb, but at a cost over the SF Line2's. I would tend to agree with Warnerwh that ARC pre amps are a good choice.They seem to match up very well with many a SS amp. I know of 2 dealers who love the ARC tube pre amps with their Pass Labs amps as an example. Also, as mentioned above, The ARC's pre's have run the spectrum from tubey to more neutral or SS sounding in their long pre amp history, as seem from their design changes (pure tube, hybrid, all SS etc.) They certainly have a more consistant sound from their amps over the years, than their pre amps. Yet, I find I keep coming back to the ARC pre amps for their refined and accurate presentation and just the right amount of warmth with detail. Just my of luck-Ken
Conrad-Johnson Premier will be amazed!!
I know you mentioned tubes, but you might want to consider upgrading from a KRC-2 to a KRC-HR. I had the same amp/preamp combo you do, and noticed a major improvement in moving up to the KRC-HR. More air, better imaging, bass tightened up; difference was fairly dramatic.

I heard one krell ksa 300s with ARC LS25 and they match perfectly.
There is a new Audible Illusions M3A for sale brand new for auction. Single ended, but a great preamp.