I have a Calypso. They ship it set to the highest gain setting which is to high for most systems. That's why there are reports of tube rush. To change the gain setting you just have to move some jumpers inside. Also the stock tubes tend to go noisy pretty quick unless you get lucky and receive a good set. I Switched to NOS and haven't had any problems at all. I've had these for almost 3 years. I listen for about 2 to 3 hours a day. So that's at least 2,100 hours and counting. I recently bought a new set to have a back up. I put these in and there wasn't much difference in the sound so I put the old ones back in.
Not sure if it's the right fit for your system but it definitely is worth a listen.
Not sure if it's the right fit for your system but it definitely is worth a listen.