Hi, the question is for me, why did they change all tubes? Preamp valves have a lifetime of up to 5000 hours , some up to 10.000 hrs. Do you still have your "old" tubes? Then you can change one by one, because most probably only one valve was faulty. Russian 6SN7 are only very good if they are made by Foton. Regards. Knut
Knut.
Acoustic Signature Thunder & Final Tool, Technics SP15, Ampearl RE1030 Valve Phono, Ampearl Valve phono LCR RE2030, Ampearl RE1031, Tribute SUT, Aidas MC, Linn Akiva, DS Audio E1, Nagra VPS
Legat Audio SETA E130L SE, Legat KT88 SE , K&T Donar, JE Labs Open baffle with Philips 12202, BK elec SUBs P12 & XXls400