12ax7 vs 5751

Grayf
The upgrades included replacement of all signal caps with V-Cap CUTF/OIMP
MUNDORF silver/gold hook up wire
WBT Nextgen RCAs for 2 inputs and output
DACT 24 STEP Attenuator

I would contact Ted at highendaudio.com for any upgrades.
He is part of the new owners of Thor Audio and you couldnt ask for a more available and polite person to deal with. I plan on sending my unit to him to do some housecleaning.
They work on all units though.
The particular unit I bought had a bit of history b/c the upgrades they offer/suggested were done by another outfit. Long story short I think I came out ahead due to the fact that Thor didnt do the upgrades...otherwise a 5 year warranty and stamp of approval would have driven the price up.
This is really an incredible preamp. My sound floor is at 1 on the volume. ALL the sound is there as soon as the volume is engaged. I was a volume hogg because I had to turn it up so loud to hear detail before. Cheap imitation.haha
I think this is a glimple of how a 30 or 60 watt amp can produce quality sound. Just for the record the new Thor will retail at around 17K and the old unit upgraded is supposed to be in the same ballpark. I feel like I got a sports car for a work truck price!
WHERE IS THAT STINKING POST MAN???????

Grayf the Treasure Z's you are getting are supposed to be a very good tube. A big step up from the EH KT88's. Now I'll be honest I don't have or heard the Treasure Z's but from everything I've read they seem to be a step down from the EAT KT88 and a step up from the EH SED and Gold Lion re-issue). I also have a few original Tung Sol 6550 solid black and grey plates. Very different - more seductive and a little less detailed. It just amazes me that I can swap some tubes and change the type of sound. In my PERSONAL opinion the EAT's are the best (won't have the Gec/Tesla for up to couple more weeks to compare). I have a pair and a quad of the EAT's (which I bought used) and after 300 hrs I only have 3 stable tubes. 2 with a bias drift and 1 that puts my Octave into protection mode. So I can make a quad but have to monitor the bias every hour or so.

OK that's the long story - Short story unless there is a real dissatisfaction with the Treasure Z's (very unlikely) just be happy with what you have. You have a lot of combinations of tubes to play with.

Have fun because tube rolling can be a real treat ;)
Disclaimer: I own SED EL34 - 6550 and KT88's Gold Lion reissue KT88 original Tung Sol solid black plates and solid grey plates - EAT KT88 diamonds and Ei KT90's. There is NO bad sounding tubes. Only better sounding ones!!!

Xti16 thank u so much for that info thats invaluable. i really will have to draw the line at the treasure tubes because of the expense. i did some digging for info on decent kt88`s yeaterday and the ones you have are a fantastic collection and i can only imagine how much enjoyment you get from all the different sounds available to you. i`m so impressed by all the different sounds i get with all these tubes i have too. it`s like a whole new world has opened up to me and i`m just as impressed with all the advice i`ve had from the tube amplifier community and i`m so pleased to be part of that.

i completely agree with you about the fact that there are really no bad sounding tubes and i can also say that what doesn`t work in my amp will work in others sound wise. but the beautiful truth so far is i haven`t really come across anything that hasn`t worked decently in my amp apart from when i switched positions of the brimar cv1988/rca vt231 6sn7 tubes but that was literally down to just switching positions.

gonna cut this short now, i just got the telefunken 12ax7`s through the post! i`m like a kid with a new toy lol. i`ll post a review of these later today guys and thankies again Xti16 for that fantastic info. chat later guys

i cannot contain myself here!!! i put the telefunkens straight in the amp and to my sheer luck i heard my neighbour that lives below me going out! talk about a stroke of luck! and these tubes? WOW WOW WOW!!! so far these are the kiddies! i put my usual fav cd on dave gilmour. more twang to his guitar, more detail, the bass growls, gorgeous tones and to my sheer surprise an even lower noise floor. i can see why these are considered as some of the very best of 12ax7`s. this sound stage just keeps getting freakier and freakier! the seperation is just spot on! deadly accurate. if these tubes can be likened to the armed forces then these are the special air service of the tube world lol. truly elite!!! the ei elites are very very similar, it`s just that these telefunkens go that extra mile and definately worth the expense and i gotta say i got an amazing bargain. i got these very cheap compared to the prices i`ve seen them go for. god only knows how the ge 5751`s are going to stand up to these! the ge`s really are going to have to go some to beat the sound of the telefunkens......thats if they ever get here!!! oh did i mention i got the bass slam back again! the ei elites and telefunkens draw level when it comes to bass slam, i can`t hear any difference here. oh man someone please wipe this smile off my face lol my face seems to be stuck in smile mode lol. i simply cannot believe the sound coming out of my speakers! Mcpherson put these on your shopping list. these are amazing!

oh and guys these are the least bit microphonic. extremely silent. awesome!