I have just bought an Opera Cyber 20 headphone amp. I will use it with a Grado RS-2 headphones to listen, mainly, to Rock and Jazz music. Love the full and round bass sound and the extended soundstage.
With all the previous information, I would like to leverage a bit your experience with this amp. I plan to play a bit with "tube rolling", but I am an absolute newbie to this tubes in general and tube rolling in particular and prefer to have a quality starting point that allows me to play a bit having a safe bet.
Which tubes would you recommend me for the previously described combination?.
Many thanks for your advise. Best regards,