You might also try as driver tubes three Philips E80CC tubes made in Heerlen. These are 12au7 subs with a higher filament current requirement which works fine in the 160iSE amp, but only in the driver section and importantly not in the preamp section on the left. I have used them for a couple of years now and like them a lot. These Philips Heerlen E80CC tubes are identified by a delta symbol in the 4 or 5 digit tube serial number marked on the glass near the base. Philips E80CC Heerlen tubes were also marketed under the Valvo, Telefunken and Siemens names, but so long as they have the delta in the serial number they were made in the Philips Heerlen plant which is where they were apparently made best. They produce a more powerful, clarified, detailed presentation with the sound perhaps a bit more forward than you would get with standard 12au7s. I like them better and use only these in the driver section. Please do not use one of these E80CC tubes in the left hand side preamp section. A pinched glass version of these tubes can run a lot of money - hundred of dollars each, but I use just the normal versions which can run you about $50 apiece on EBay. I use 2 or 3 of Herbie's HALO-III tube dampers on each tube which may be similar to the the pinched glass effect.
