Andy is great. But, has top-notch NOS tubes...is expensive...knows he is expensive... and thinks he is worth it - having bought $1k worth of tubes from him, so do I. By all means, get a price.
However, for someone who is concerned about $6 and has a $1k -$2k preamp, it may be a better recommendation to more directly answer your question with, "Low noise and microphonic, and matching".
Additional consideration- The Tube Store , new tubes mainly, and online audiogon Quebec vendor, "Mathieuvarian", NOS, have proven themselves as well.
However, for someone who is concerned about $6 and has a $1k -$2k preamp, it may be a better recommendation to more directly answer your question with, "Low noise and microphonic, and matching".
Additional consideration- The Tube Store , new tubes mainly, and online audiogon Quebec vendor, "Mathieuvarian", NOS, have proven themselves as well.