Changes or improvements of sound quality from Mullards CV4003??

I was advised to change out the output tubes in the current Rogue Sphinx integrated amp with Mullard CV4003 tubes. One or two members have mentioned  this change, claiming it would cut down on the "glare"  indigenous to a Hypex Class D amp used in the Rogue Sphinx amp.  Therefore, would appreciate any feedback from members who have made this tube change.  BTW, I have a new pair of  Golden Ear Technology model 7.speakers  

  PlLEASE NOTE:..... Rogue is now shipping the Sphinx version 2 integrated which supposedly has three improvements over the original: 1) a lower overall noise floor, 2) increased volume in the headphone output, 3) greater volume sensitivity with the MM phono stage;  4) a new plastic  "skeletal" remote that has added a mute switch.

 All admirable changes on their part,. but very bad because the new version lowers the re-sale value of the original. Upgrade plan cost $ 400.00 plus the round trip shipping costs ( approx.$115 from West Coast to Rogue in Pennsylvania)

 To cut to the chase:  This makes me more than somewhat reluctant to pour more money into the unit  by adding the Mullards to the current non-upgraded version which I have. Therefore,  Mullards and upgrades would cost approx....$700-715.   

 BTW, with the Holidays and CES ahead, Rogue informed me upgrade turn around time would be at least  4-5 weeks.  Am I between a rock and hard place??    Thanks to all          

I can't speak to the Mullard's sound in the Rogue, but that tube, (Mullard CV4003) is my favorite 12AU7 tube.

I use that tube in several different pieces of gear.  I bet I have at least a dozen of them as back up.

IMHO, the best 12AU7 tube out there.
I use the Mullard CV4003 tube in my Rogue Cronus Integrated and it is IMHO the BEST 12au7 tube out there.  Highly recommended.

Thank you for the testimonials. Does it make any difference if the tube has been cryogenically treated??   ( Not sure what that is, unless it  is to preserve those who starred in the that film: "Honey, I Shrunk the Kids" .(LOL) 

It was mentioned by the  person who got me on  this new track.!! 

I have several pairs of different type tubes that were matched and bought from the same dealer at the same time. One pair was cryoed and the other pair wasn't.  I wanted to prove to myself if there really was a sonic difference in sound.

I can tell NO difference between them.  This after many years of comparison. 

IMHO, cryoing a tube is a big waste of money.  The only advantage that I have read about,  is "maybe" the tube "might" last longer, but I'm not so sure.

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To Mofi and other members who took the time to respond to this thread and offered advice.   Thank you.  I DID  RESPOND  yesterday and discussed the results of the using the Mullard CV4003 tubes in the Rogue Sphinx integrated amp  which  incorporates a class D design.   There were pros and cons. However, at the end of the response I referred to the indigenous edge or glare produced by class D amps, and happen to use the famous "F"WORD TO EXPRESS MY FRUSTRATION with  not being able to alleviate the problem of that design. BTW, no profanity or discourtesy was directed at any responders on this thread or others  offered in the past

  This morning I received an email from Audiogon condemning my use of profanity in the response which one of their "censors" deleted. It appears that Audiogon  has assumed the role of Big Brother, and I awaited to be dragged away to the Ministry of Fear for further interrogation.

Audiogon who has over the last three years, constructed a confusing, difficult to navigate web format, and initiated a dramatic increase  in fees, has found yet another way to alienate members, or at least one member   Therefore, I wanted to assure those who provided later responses that they were not ignored or forgotten.  I am not sure if I can .continued on a blog that is incompetently run,. greed driven, and has established policies and guidelines that are rigid, senseless, and possibly illegal  

 Nevertheless, I don't have the energy to reproduce my response which was deleted; but I want to thank everyone over the years who have provided me with valuable advice and comments about audio equipment. I also appreciate the patience of many members who put up with some of my repetitive questions and inquiries

Good Luck to all, and Happy Holidays!!    Jim