Buy 12ax7 tube

<!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:-536869121 1107305727 33554432 0 415 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-536859905 -1073732485 9 0 511 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin-top:0in; margin-right:0in; margin-bottom:8.0pt; margin-left:0in; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoPapDefault {mso-style-type:export-only; margin-bottom:8.0pt; line-height:107%;} @page WordSection1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.WordSection1 {page:WordSection1;} -->

I own both the Raytheon & RCA black plate 12AX7’s and both (IMHO) are better than any new production 12AX7 tubes. For what it’s worth the RCA’s black plates are my favorite 12AX7’s. The RCA’s are on the mellow side but plenty of detail. I also own Mallards and Telefunken and to my ears the RCA’s are somewhere in the middle. Another great low distortion tube especially in the phono section is the RFT 12AX7.

First of all, I must say that it's preferable to buy tubes from a reputable dealer who's stock will be high quality and guaranteed. Tubes from a Chinese website may not be genuine or may not test as new or NOS. There are plenty of good, inexpensive dealers on Ebay.

Regarding your tubes, I see the Vincent uses 3 12AX7s (ECC83) in the preamp stage. I assume you are  replacing all 3. 
Telefunken are the most neutral and linear, but expensive. RCA Blackplates are affordable and offer a sweet midrange with good dynamics, $40 to $50 each. Raytheon is a low noise tube with open sonics. I would choose these NOS tubes over Genalex.

You'll want these tubes to be matched since they're in the preamp stage.

A reference for the 12AX7...
https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html#12AX7

On Ebay, Viva Tubes is a reputable dealer with good prices.
Brent Jessee has everything.

Don't discount these for new production. They have bested a lot of NOS in my phono pre
SVETLANA 12AX7 

Most of the tubes I get are from Brent Jessee; have also bought from Tubeworld. I think the guy is Brandon. Good products from both.

That's interesting about the Svetlana 12AX7. They are famous for making the highly rated  Winged C EL34.