Tube rolling for Hovland HP-100 w/phono pre, 12AX7 12AU7

Does anyone has any experience tube rolling a Hovland Hp-100 with the MC phono pre? What difference did you get compared to stock? I find the MC phono section a little noisy.

Where to buy them?

Thanks in advance for your answers
Not a good idea. I was talking to the company as i saw your post
I just have the line stage. I bought some Mullard 12AX7's from Kevin Deal at Upscale. While I wasn't experiencing noise problems, I thought I could give some more body and dimension to the presentation. All it did was confuse the sound. Have you tried switching off the front panel light? I know that contributes noise that Alex says is "electrostatic noise".
If you are looking for a fuller, richer sound, I suggest Telefunkens, if you are after a bigger, more dynamic, more vivid presentation, then I'd suggest Amperex Bugle Boys, or Siemens. The best 12AX7 made, were the Telefunken ECC803s, which are very rare, and very expensive.Probably, if Hovland could, they would use Telefunkens, as these are universally regarded, as the best 12AX7's ever produced. Check out my ads at Audiogon.