@bzawa , Hi , unfortunately Rogue like many ran into a tube supply issues. The Dark Rogues used to have Tung Sol KT 120’s, Telefunken 12AX7’s and RCA 12AU7’s. They ditched the Tung Sol’s due to availability and reliability issues. They ditched the nos input/phase/driver tubes due to lack of availability and exorbitantly high prices. Your amp will have more bass and power with Tung Sol KT 120’s, but less treble. The two 12AX7’s will have the most influence on your tonality. Last summer I had my Rogue M-180’s updated to “ DARK “ , Rogue tubed them with new production Tung Sol 5751 gold pins in the 12AX7 slots. I subbed a $300 pair of nos Telefunken 12AX7’s and it was too bright. I really like the Tung Sol’s but they have a mu ( gain ) of 70 and 12AX7’s have a mu of 100, hence a bit less output, but a smoother sound with less noise. If you’re willing to spend the money try Tung Sol KT 120’s X 4, new production Gold Lion 12AU7’s. Try the 5751’s or a nos set of 12AX7’s ( not sure what ) or the 5751’s. All said you’re looking at $1K to spin the wheel. FWIW I’ve been told by @mulveling there is a Rogue owners group on Facebook. I also tagged him on this as he’s a great source of humble knowledge regarding Rogue Gear. Respectfully, Mike B.