Rogue Cronus with KT-90 tubes

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 !!