I saw NOS Mullard CV4003's at a fair price of $155.00 including shipping.
I just received them on Monday and installed them on Tuesday.
On another subject I was having problems with TIDAL and drop-offs for about a week since their latest update. Getting a response from TIDAL is a test in patience mostly b/c of their location.
Finally, yesterday I was able to fix the problem which I have to admit was NOT as it turned out a TIDAL issue, nor an APPLE issue since I use a 4gen iPad and APPLE TV, but I decided to call APPLE for assistance.
Simple put I was on airplay mirroring not airplay which was located on another screen which I was unaware since this latest update, point of mention is that TIDAL is displayed differently on newer iPads.
Ok, now the CV4003.
I removed the 5963 in the phase position entirely.
I moved my GE 12BH7A into the phase position and the Mullard CV4003 into the driver/volt amplifier position.
The difference was immediate! I do believe in tubes burning in but I know what I heard and I was very pleased. It seems the CV's do an outstanding job in the midrange especially but also it includes the tweeter. I have read that the Mullard CV4003 relaxes the top end a smidge but to my ears it was unnoticed. Besides how do you measure a SMIDGE? Another great tube is the Brimar CV4003 however I am sold on the Mullards and the lack of sustaining air on the top does not seem to be an issue at least for my listening tastes.
Just wanted to share my experience. I love these m125's even more.