Pream question

A few days ago I got Audio Research LS-5 MKII for testing. The sound seems good for me so I decided to buy it. But right now there are two more preamps in the same price range at our local market: Audio Research LS-25 MKII and Balanced Audio Technology VK-51SE. All have quite positive feedbacks... What will be the best choice among these three?

My current system is: B&W Matrix 803 S2, Luxman Da-06 DAC and Luxman M600-A amp.
While both the BAT and ARC are fine preamps, having heard both myself I'd say the difference in their characters is very marked. The BAT is very neutral, closer to a really good solid state unit than the classic tube sound. The LS5, on the other hand, is probably the closest thing to a classic tube-sounding preamp that ARC made since the SP10; as a result, it has a lot of admirers. It seems to me from what you've written so far that you prefer the classic tube sound, so I'd suggest you stick with the LS5. Re-capping the BAT will change its sound, but I don't think you'll get it to change its character that much, only improve on its existing character. Just MHO.
Everything is well with CAPs - the problem was with bad soldering. That's a good news)

Spent some money and got NOS P-DR tubes. Will try them during the weekend...
Well maybe something is wrong with my ears or with my system or with BAT amp... The new DR tubes made the sound better (a crazy price for 35 years old soviet stuff btw...) but still I'm not satisfied. The sound of LS5 is more detailed, more "surrounding" imo. Also the volume level of BAT isn't so high: it's absolutely comfort to listen with 50% of maximum level while with LS even 30% is very loud.

Should I give the new tubes more time to play? Could it be the problem because of using rather simple step down transformer?

I don't want to return or to sell BAT right now - at least it looks rather good)