Pream question

Can anyone tell me what caps should I use for 51SE as a replacement? Is it 0.1uf 400v or 1uf 400v by Jensen?

How do you know that the caps are the problem? I know that I recommended the Bat, but sometimes things don't work out. I was kind of surprised that it didn't sound good for you. The last thing I would recommend for you to do is put money into an expensive preamp that you've never heard sounding good. There's other choices, and not only that, you really don't know if there is anything wrong with it.

That said, if you want to look into Caps, I would contact Bat. They're known for offering Cap upgrades, and if you explain to them the problem, they may be able to give you some good advice. Bat does have a very good reputation. I don't think they would mislead you in any way just to sell a preamp.

Like talking to the wall...

There is a permanent noise coming from the left block of caps. I took the amp to the service center and I'm waiting for their conclusion. In case the problem is with caps - it's better to start searching for the replacment parts now as I doubt that it will be possible to find the original Jensen in our country)

Btw I replaced all the tubes with Electro-Harmonix 6H30Pi EHG. The sound is better now but still far from LS5ii imo...

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.