Tubes types/do they make a noticeable difference

I have been thinking of retiring my KT 88's and investing in a couple of quad KT 120's but I have not decided to make the leap. Yes monies are part of that decision but also I have to say my system sounds so awesome now I think how much of a difference will I hear? Is it cost effective? I still ponder this question given I am talking about OUTPUT TUBES.

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.
blue

nice to know, but why so much $$. TubeDepot.com sells NOS Mullard CV4003 for $99 each and about $4 shipping

tubes4hifi wrote:nice to know, but why so much $$.   TubeDepot.com sells NOS Mullard CV4003 for $99 each and about $4 shipping

I paid $155.00 for 2 NOS CV4003's and that includes shipping.
I think I got a price better than than Tube Depot...my math tells me I would have paid $202.00 with shipping.

Blue, in answer to you instant question, Tung-Sol KT-120s are actually cheaper than Gold Lion KT-88s. I have tried both varieties; the KT-120s sounded better and more throaty in the M-125s. It's more a matter of taste than expense. I'd go to Jim McShane for counsel on that. Also, consider the top-grade KT88z's out of China. They are excellent as well but don't have as long a track record.
IMHO, it's the choices you make for the driver and pre-amp tubes that will have the most influence on the flavour of sound.
The beauty of Bob's M-125s (and the ST-120s) is that they accept such a wide variety of output and driver tubes: you're not stuck with a simple A/B choice.
Brains far greater than mine differ on driver configurations. Bob L. prefers the noval board; Roy M. prefers the octal board. They can't both be right or wrong. Experimentation, listening environment, and speaker loads will determine what's best for your ears.
Glad to hear you're lovin' those M-125s.
Cheers,
Dave

deepee99 wrote:Blue, in answer to you instant question, Tung-Sol KT-120s are actually cheaper than Gold Lion KT-88s. I have tried both varieties; the KT-120s sounded better and more throaty in the M-125s. It's more a matter of taste than expense. I'd go to Jim McShane for counsel on that. Also, consider the top-grade KT88z's out of China. They are excellent as well but don't have as long a track record.
IMHO, it's the choices you make for the driver and pre-amp tubes that will have the most influence on the flavour of sound.
The beauty of Bob's M-125s (and the ST-120s) is that they accept such a wide variety of output and driver tubes: you're not stuck with a simple A/B choice.
Brains far greater than mine differ on driver configurations. Bob L. prefers the noval board; Roy M. prefers the octal board. They can't both be right or wrong. Experimentation, listening environment, and speaker loads will determine what's best for your ears.
Glad to hear you're lovin' those M-125s.
Cheers,
Dave

Thanks Dave...more to think about.