The mighty CAT preamp

has anyone gone and replaced a CAT with something else

I have. With a FM Acoustics 155. It is better in all respects.
This said, my CAT was a top-notch preamp. Far removed from the plethora of mediocre machines out there. BTW, I used a 3, then an Ultimate.

"has anyone gone and replaced a CAT with something else"

I have. Joule-Electra LA-300ME. While, sonically "300" is much better (which is question of the personal taste) there are other factors tilting toward Joule-Electra.

a) I always could hear tube hiss using CAT and I spent crazy money to find ultra low noise tubes, It drove me crazy and I compalined to Ken Stevens many times...

b) The cost of re-tubing. With CAT, I had to retube bi-annually and with "300" once per 5-10 years and if your amp has input impedence > 10 kOhms then this time will double. The best NOS tubes for "300" cost $70-$100 from Joule-Electra, CAT NOS tubes cost was at least $400 - $500 (Ken always provided the best contemporary at reasonable price)

c) I always "hated" CAT's outboard power supply firm connection to the main chassis. "300" - is one box solution, has tube in power suupply (i.e.more liquid sound) and has better bass...

d) I have to wait at least one hour for CAT to warm up whereas "300" has stand-by feature. You want to listen, just flip switch and 60 seconds later - everything is at its best.

I must say that CAT was and still is mightly preamp, one of the best in the world and anybody who uses it must be in audio heaven. Simply its not the best in the world for me, personally.

That's very interesting Spectron. I personally have not had to re-tube that often, in fact I have had my current tube set about two years and all still seems fine. I do agree that at certain gain levels the CAT is not dead quiet, some slight tube hiss is audible when nothing is playing. OTOH, I was amazed at the improvement that was had when I changed from the 'stock' tubes to the current NOS GE Smooth plates.
What other components are you using with the Joule and are they the same as when you had the CAT?

"What other components are you using with the Joule and are they the same as when you had the CAT? "

With CAT I used Equilibre, tube amp from Audio Matiere (now, I believe its Audio Aero) and I also used the Spectron Musician III (standard) stereo amplifier. I owned different CATs for about 15 years, indeed mighty cat and difficult to think that can be any better....

With Joule-Electra I use only Spectron amplifiers - monoblocks with all upgardes.

Best Regards
Simon