Allot of the Chinese tubes tend to get noisy within a year, this is my experience with the MP-1. Whilst these Tubes will work in other pre-amps and not show any sign of noise. It will instantly be apprently on the MP-1. So you must feed it good stuff.
MP-1 is so sensitive and revealing it has to be carefully matched and setup. Once this aspect is done right it will go toe to toe to anything costing even 4 times its price tag easily!
Patient is required on the Atma-Sphere Gear to get Proper setup done. Especially the Pre-amps.
Iv borrowed, purchased and sold countless Pre-amps but the MP-1 is a keeper. The Phono Stage alone on this pre-amp will challenge phono stages at any price too.
Whilst sonically it is a marvelous peice of gear, it will reward its owner with years of musical enjoyment. It can be tricky with tubes. Allot of the stuff from china have bad quality control and you can end up with noisy stuff.