Just bought one Ms-12b on ebay....i've immediatly changed the provided tubes with 2 12AU7 from La Radiotechnique 1958, and 2 Sylvania Brown 12AX7....
The result is just incredible. Really, i didn't thought that the music will be so improved. My first impressions are more into what it improved either about what it really adds. And i think that's a really important matter with this preamp. It won't change the sound you already have, it'll drastically improve it. It'll keep the original flavor of your sources, and that's very important to me, because i didn't want something that adds a personnality to something that already have one. Just think about your wife, with make up and without
It's the same woman without, but with it, it's better...although the make up is great for sure. It's the same here.
I'm feeding the MS12B with a Marantz CD6000 and a Project Perspective with a Shure Vn5vxmr. The ms-12b feeds my Marantz PM7200 (love the marantz sound...) and two Quad 11L speakers.
For this price, it's not just a bargain, it's a must have !!
hope this helps