Thank you guys for all the recommendation on rectifier tubes. Looks like my brand new but annoyingly buzzing stock tube is going to be replaced soon. If I look up the Mullard GZ34 I seem to find 10000 diffrent ones, with diffrent shape, price etc. Could you please link me the one I should look out for exactly? EDIT: I'm guessing this is a quality replica of the Mullard you've mentioned: http://www.tubeampdoctor.com/produc...=386&language=en&mySID=jTuJkj-B-Cm7HEtxYLuNK3 http://www.tubeampdoctor.com/de/shop_Sonstige_Markenroehren_Gleichrichter/5U4G_5C3S_5_3C_NOS_blackplate_595 Is that the same one, Gefski? I'm happy to have found this shop that actually is selling from Germany!