Aesthetix Calypso Tube Rolling

I am now auditioning an 2004 vintage Aesthetix Calypso with very good results.

The Calypso has great detail but with a smooth sound (CD's sound better)

I opened up the preamp and found Holland HAMMOND 12AX7 (I think these are considered good tubes)

The 6922's in the unit are Sovtek, thus I think I would upgrade to the GENALEX Gold Lion

Others have suggested the I also consider the Gold tIp Tung -Sol for the 12ax7 tubes, other suggest the Gold Lion 12ax7.

I an not sure I need to make a change as the preamp sounds good, I think I might try thr Gold Lion 6922 before swap out the Holland/Hammond 12ax7 tubes
One point I can make is that Holland/Hammond 12ax7 are NOS Amperex tubes which if they had the Amperex name on them, would be very expensive. These may not be the premium Amperex, (like Bugle Boys), but provide a 3D soundstage, good bass and sweet mids. Amperex made tubes for Hammond, Harmon Kardon and many others.
I would roll the Sovteks first. Happy listening.
Here is a link to a discussion of your question:

The made in Heerlen, Holland Amperexes are very good tubes. They were sold under a variety of labels but can be identified by a left facing right triangle etched into the glass. I would be worried that yours are getting old given the age of the preamp. I would get them tested if you can. The consensus of the discussion linked to above is that the 12AX7 contribute more to the sound quality than the 6922s. So you might want to try a pair ofgood quality current production 6922s and try some different NOS 12AX7s.

Good luck and Enjoy!