I have 3 Jadis integrateds, an Orchestra Reference, Defy DA30 (grandfather of the DA50S), and a DA60 (father of the DA88S). I own other amps, and have owned many amplifiers, both tube and solid state over the past 20 years. In my experience, Jadis amplifiers have proven more sensitive to tubes than any I’ve encountered.
Though the Defy DA30 / DA50S sits further up the ladder than the JOR, it does not produce as much power or bottom end. Art Dudley also mentions these in his review of the JOR. Your amplifier focuses on sublety, not brute force. In my experience, Legacy loudspeakers work best with higher output solid state amplification, and don’t couple well with low to moderately powered tube products. Sensitivity makes up one part of the loudspeaker - amplifier match. Impedance, phase angle, and crossover topology play an equally large factor. I’ve found my Defy 30 not at all a hot rod, and this match just doesn’t feel especially good to me. If you wish to hear what the Jadis can do, you may want to consider a more tube friendly loudspeaker, or moving on from the amplifier. The former should set the stage for you to begin to experience the beauty of Jadis.
Aside from that, personally, I would first try JJ E34L, JJ EL34, Shuguang EL34B, ElectroHarmonix 6CA7, Shuguang Black Treasure 6CA7-Z, or British made vintage Mullard EL34 output tubes, as I find Jadis integrateds to sound best with EL34. Outside of the Shuguang 12AX7B / Silver Dragon, most vintage 12AX7 better what recent amplifiers run, and that’s the next tube to change. If you don’t want to make much of an investment, but still hear the amp move forward, replace the drivers first, and keep the KT90 for now. Lastly, the 12AU7 input tubes, though I find the aforementioned tubes the first to address
Though the Defy DA30 / DA50S sits further up the ladder than the JOR, it does not produce as much power or bottom end. Art Dudley also mentions these in his review of the JOR. Your amplifier focuses on sublety, not brute force. In my experience, Legacy loudspeakers work best with higher output solid state amplification, and don’t couple well with low to moderately powered tube products. Sensitivity makes up one part of the loudspeaker - amplifier match. Impedance, phase angle, and crossover topology play an equally large factor. I’ve found my Defy 30 not at all a hot rod, and this match just doesn’t feel especially good to me. If you wish to hear what the Jadis can do, you may want to consider a more tube friendly loudspeaker, or moving on from the amplifier. The former should set the stage for you to begin to experience the beauty of Jadis.
Aside from that, personally, I would first try JJ E34L, JJ EL34, Shuguang EL34B, ElectroHarmonix 6CA7, Shuguang Black Treasure 6CA7-Z, or British made vintage Mullard EL34 output tubes, as I find Jadis integrateds to sound best with EL34. Outside of the Shuguang 12AX7B / Silver Dragon, most vintage 12AX7 better what recent amplifiers run, and that’s the next tube to change. If you don’t want to make much of an investment, but still hear the amp move forward, replace the drivers first, and keep the KT90 for now. Lastly, the 12AU7 input tubes, though I find the aforementioned tubes the first to address