Atma-sphere tube?

Low noise is the first priority, section balance is also impt. I found real sonic improvements with NOS versions of all the preamp tubes, though certain of the 6SN7s impact that more than others. Tube dampers also work well in this application - I use Herbies. There are 8 12AT7s in the MP-1 with phono - consider yourself lucky :-).

Ralph may tell you there are no more quiet NOS 12AT7s, but I have real good results with these:

* Siemens Halske 3 Mica E81CC (Tubemonger.com) - very clear w/ nicely extended top end and transient definition
* Sylvania 6201 (Upscale Audio)- excellent all around
* Mullard CV4024 (Jim McShane)- rich instrumental and vocal timbre

 
Tim

Sure it has an impact on the sound.Different brands will have their own sound,it's up to you to decide what you like.Not all tubes touted to be "low noise" are.Again,you will have to decide what you like.

I'd check with Ralph first. He's one of the truly good guys of audio and a real straight shooter. Hope you enjoy your MP3 -- I had one for a number of years and found it immensely musical and fleible. -- Bill