Rogue Cronus with KT-90 tubes

Has anyone tried these tubes and how do they sound compared with EL-34?
Call Rogue Audio at (570)992-9901.I think the people that made the equipment can give you the best advice.Good luck.
Lamcam - I may be wrong but I think that unless you have the Magnum upgrade you can't use the KT 90s - the Magnum version is 90 wpc versus the 55 wpc of the standard model and comes with the KT90s- Double check this with Mark at Rogue.
Thanks for your responses! I have checked with Rogue about the tubes, they said it will be ok to use KT-90. I just want to find out from users about the sound I will get.
But also do try JJ KT77s. I did in a Cronus I used to own and they made a positive difference.
I'm surprised that Mark said the KT-90s would be fine. So if one can just swap them in, what else does the Magnum upgrade add?

Stevecham - what different did you notice with the JJ KT77s?
I'd check again about the standard versions use of KT 90s - see below from their site re Magnum upgrade

from Rogue site - for Cronus which is in Titan series

The Rogue Audio "Titan MAGNUM" Series
The "MAGNUM" versions of the Titan series features significant parts upgrades that improve performance in your Atlas, Metis or Cronus in a number of important ways. Increased transparency, greater dynamics, improved bass and high frequency response, as well as a smoother and more refined presentation are all part of the Magnum upgrade. The extensive power supply mods permit the use of the KT90 power tube which increases the rated output power of the Atlas and Cronus to 90WPC!

The Magnum package consist of the following modifications:

Atlas and Cronus Magnum:
- Larger power supply
- Power supply mods
- Polypropylene bypass capacitors
- Precision Dale-Vishay resistors in critical spots
- Upgraded binding posts
- Gold tube sockets
- Upgraded small signal tubes
- KT90 output tubes

- Magnum logo on faceplate

I have the Cronus and used it with EL34's (ElectroHarmonix) which I loved, then upgraded to Magnum with the KT90's. I could easily be happy with either. I loved the dimensionality and warmth of the EL34's, but the KT90's just give way more a sense of "in the room" sound of musical instruments.
I still have the stock Svetlana EL-34's in my Cronus. HOWEVER.....for me, a significant improvement in the all-around musicality of the amp came from swapping out the original five "small tubes" for a set of NOS RCA and GE tubes hand picked by Mark and Nick at Rogue Audio. For less than $200, I feel like I really upgraded my amp, and made my Vandersteens sound even sweeter. Just a thought......Good Luck, and Happy Listening !!
When I received my Magnum it came with NOS Sylvania 12ax7 & 12au7s, sounded pretty good , have since swapped them out for RFT 12AU7s and Tungsol 5751 (12ax7) and prefer the sound - RFTs to me anyway have a more similar sound to RCAs
An update after living with the KT 90's in my Rogue Cronus Magnum I swapped back the EL 34's for a comparison (biased them properly, of course) and the result?

Can't wait to put the KT 90's back in. I think Mark & Co. knew what they were doing when they built the upgrade around that tube: light high end, tonally pure mids, strong controlled bass, nice sense of space. Listening to a live concert last week from the Benaroya Hall (where I regularly listen to the Seattle Symphony live) I heard someone cough and could identify how far back in the hall they were seated. I am done with messing around with tubes, on to optimizing my LP area now.
I have recently replaced the original Svetlana EL-34's with a matched quad of Genelex Gold Lion KT-77's, following the advice of Mark O'Brien and many "tube gurus" out there in audioland. The result are sublime. As much as I loved the Cronus before, I've brought it up to a whole new level. See my post on this thread from 11/20/09.
Happy Listening !
Do you think the Cronus with Kt 90 tubes can drive the Maggie !.&'s which present a more problematic load than the 3.6's? It would be marvellous if it could. There is also the Cary sli 80. It would lengthen my budget. Thanks