Sonic Frontiers Power 2&3

Has anyone actually replaced the 5687 tubes in the Power 2 & 3 with 6900 tubes? I need to know if any modification was used or was it a drop in replacement.

On the output tubes, what tubes have you tried other than 6550 or KT88? (your observations)
~~~~I have been wondering the same thing. Anybody know about the 5687 to 6900 compatibility, did anything need to be upgraded?

Just The Facts
I have changed all tubes in my Power2 and now is really immense:5687 RCA faceplate,6922 Siemens,KT88 Electro Harmonix( better than Svetlana,more power,more reliable.)
Piero Italy
~~~~Update. Have been using 6900's now for 3 mos. Must keep checking bias on output tubes as 6900's warm up and burn in. They take 5 minutes or so to fully warm up. Took few hours to burn in and stabilize. Nice improvement in sound.

Just The Facts!