I bought a matched pair of these for my 1987 Marshall 2554 Silver Jubilee combo. Well if you have a 2554 (or any Marshall for that matter) you should definitely try them out. Before I installed those, the amp had a pair of the so-called "Winged Cs, or =C=" EL34 tubes and I can honestly say that these are equally good sounding (if not better) than the =C=. The Bass sounds huge and tight with them, the mids are very strong and open sounding and the highs are sparkling. It is a very well balanced tube and the build quality seems top-notch. On another note, the manufacturer claims that these have a "hint of 6L6" in them and from my experience this is true especially when playing cleans. To conclude and with NOS =C= costing stupid money nowdays, these are probably the best current production EL34 out there.