Thanks to all for your answers. I know the P10 sounds better in balanced input option since a phono pickup is a inherently balanced device. Finally I decided to reterminate my phono lead (SME Din Van de Hul D501) with XLR plugs that I cannibalized from an old unused interconnect, everything works perfect now. But I like to have my components complete as deliverd by the manufacturer, so I can make my own shorting XLR plugs.
The B.A.T. VK-P10 is really a superb phono stage, it's the second time I own one, sold the first to try something else (Pass XONO) but I prefer tubes, so I am keeping this one.
I have laid my hands on 2 new/NOS matched/balanced pairs on 60's grey plate Siemens CCa, so I have a special set for great occasions. I am also ordering a brand new set from B.A.T. I am wondering if changing the the 6SN7 can make a difference? As far as the 6S45, I think there is only one source for that tube, but some say it could be substituted for Western Electric 437A.
Thanks again for all the info.
Serge