Please help Lak with a tube problem:-

I own a pare of Cary 2A3 monoblocks that came with JAN 6Sl7WGT (Philips ECG 34167) tubes. I replaced those tubes with NOS Sylvania 6SL7WGT tubes.

My JAN 6SL17WGT tubes sounded good and I could achieve the volume of 85 dB on the -1 setting of my preamp. With the NOS Sylvania 6SL7WGT tubes I have to use the setting of +4 to achieve the volume of 85 dB and the music sounds as if a vail is over the speakers.

HELP! What’s happenings? I thought I purchased the correct replacement tubes.

My system can be viewed on Audiogon, user name Lak.
Thanks for any assistance...