Tube Amp Noise with Klipsch Cornwall II

The horns that Klipsch used are brutally efficient/bright, and any noise upstream(like the preamp section of the integrated) will be brought out without mercy. Replace the small signal tubes with "Platinum Graded" ones from Upscale Audio, ie: the choices here- (http://www.upscaleaudio.com/12AU7ECC82_c_44.html) and (http://www.upscaleaudio.com/b12AX7ECC835751b_c_40.html) If you click on the tubes, you will be presented with the various grades available. While you're at it; upgrade to some quality NOS tubes and you'll be rewarded with a much improved presentation.

The sensitivity of the Klipsch is going to drive you crazy with tubes. There will always be noise, how much will depend on the tubes. You may be in for a lot of 'tube rolling' before you are satisfied. Your search for a quiet amp may be endless.

Well don't get discouraged. The others are right but you can have tube amps with your Klipsch and still have a decent noise floor without too much difficulty. My neighbor has LaScalas that are even more sensitive than your Cornwalls and we haven't had that many problems finding tube amps (and tubes) that are quiet enough.

Keep in mind though that some amps just inherently have a high noise floor, so you may not be able to save all of them with quiet tubes. I had a Rogue Magnum 99 for a while and it was pretty noisy, even with my 91dB sensitive speakers....

You made a great choice of speakers though! You have the potential of higher resolution than the majority of other stereo systems with those Cornwalls. Get them right and they'll knock your socks off.

Arthur

Not an enlightened suggestion on my part but it might be worthwhile to call Mark at Rogue and see if he has speciifc NOS tube suggestions, or other ideas.

Prefacing this that I have a Cronus Magnum but it is driving 89db Tylers - Rogue had installed NOS Sylvania 12ax7 and au7s when they sent me the amp; and I currently have Siemens and Tungsols via Upscale in it now - like it with either "version"

Sell Rogue.
As previous posters mentioned, your vintage Klipsch will pick up virtually any minor oscillations of the amp.
Technically I would experiment with adjusting feedback (obviously lowering the gain factor which may significantly help avoiding noise) along with adjusting bias current to the specified level of the THD which is more like re-tuning the amplifier.