Good question, normally I would recommend you contact Bob @rb2013, and get some NOS vokshods. The best tubes , for classical, that I use in my Lyr2 , are my NOS Telefunken E88CC platinum tubes . Those tubes can be extremely expensive, so I also use Telefunken TK E88CC tubes. The current production Telefunken TK Black Diamonds, after 200 hour burn time, can sound every nice with good classical and jazz. I use the Telefunken TK for everyday listening of jazz and classical. I use my NOS Telefunken tubes for special occasions. And if you can get NOS tubes, go for it, they are magical. The current production tubes like Genalex Gold Lions and Telefunken TK are very nice but are blown away by NOS tubes. I hope to get some more NOS tubes sometime soon. I say get them now, before its to late.