i have 2 preamps- bat vk50se and arc ls25mk11. i want to sell one of them. im leaning toward keeping the arc. it seems to have more resolution and a better top end. however ive heard that the upgrade of the bat to vk-51se is a vast improvement. anyone else have any listening experinces between these 3 preamps. my power amp is plinius 250 mk 4 and speakers are SF extremas. it just seems in my system the arc is a little more detailed and not as warm as the bat.
I just did a 50se to 51se update. Wow. It's real big. Much much better resolution, much deeper bass, tighter bass, more depth, airier-sweeter top end. I loved my 50se, but this is a steal for $1300. Takes about 2 weeks to breakin.

This looses the slight darkness the 50se had. In the end it's a system matching thing, however, I think the 51se competes with the ARC Ref not your ls25.
Part of the issue might be the relative darkness of the SF. If you ever switch to a speaker with more top enough emphasis, the ARC might make it seem too much of a good thing. I like the BAT gear quality and think it will give you more freedom if you upgrade speakers later.
The ARC is great stuff, but IMHO, more system dependent.

Follow up your ears and soul. Even BAT has a roll-off on top end and volume dependant if you trust stereophile's measurement. I bet none of equippment is perfect, and choose whatever you like. A upgrade of $1500 then changing your speaker and amp? That's a start-over again and many unknown ??? there. Everything is system dependant including BAT. I don't think anyone should do this for one particular component of particular brand, neither ARC or BAT.