FrankC,
I have trided Amperex(Bugle boy) 6DJ8's, Mullard 6DJ8s(RCA branded, made in GB) Siemens 6DJ8s(RCA branded), Siemens ECC88s with gold pins, Amperex A frame ECC88s, and Philips A frame ECC88s. For comparason, I have tried Amperex USN 6922(US made), Amperex E88CC(Holland made), Siemens E88CC(Germany), Amperex E188CC(Holland), Siemens E188CC(Germany), and Philips E188CC(Holland). Equipments I used these tubes are LS15 and PH3SE by ARC(both of them with significant resistor/capacitor upgrades). Also when I had enough tubes, I also used them in S.F. Power 2 and compared them for amplifer usage(only have done in Amperex Bugle boys 6DJ8s, Siemens ECC88s with gold pins, Amperex E88CC, and Siemens E88CC.)
For all three brandes, Amperex, Siemens, Philips, 6DJ8s or ECC88s sounded the best compared to their 6922/7308/E88CC/E188CC counterparts(I did not have set of Philips 6922s), very subtle but noticeable. I'm in process of getting some Mullard 6922s to compare the sound with RCA branded Mullard 6DJ8s.
I have trided Amperex(Bugle boy) 6DJ8's, Mullard 6DJ8s(RCA branded, made in GB) Siemens 6DJ8s(RCA branded), Siemens ECC88s with gold pins, Amperex A frame ECC88s, and Philips A frame ECC88s. For comparason, I have tried Amperex USN 6922(US made), Amperex E88CC(Holland made), Siemens E88CC(Germany), Amperex E188CC(Holland), Siemens E188CC(Germany), and Philips E188CC(Holland). Equipments I used these tubes are LS15 and PH3SE by ARC(both of them with significant resistor/capacitor upgrades). Also when I had enough tubes, I also used them in S.F. Power 2 and compared them for amplifer usage(only have done in Amperex Bugle boys 6DJ8s, Siemens ECC88s with gold pins, Amperex E88CC, and Siemens E88CC.)
For all three brandes, Amperex, Siemens, Philips, 6DJ8s or ECC88s sounded the best compared to their 6922/7308/E88CC/E188CC counterparts(I did not have set of Philips 6922s), very subtle but noticeable. I'm in process of getting some Mullard 6922s to compare the sound with RCA branded Mullard 6DJ8s.