Two 12B4As and 12AT7 (or 12DT8) work just as well, use the same DC voltages, resistors and OPTs, I built up that configuration a few years ago.
On the left is a 12B4A / 12DT8 SET, the "Darling Killer" built on and into a 4.5X7X3 inch cast aluminum Bud Box. The power supply (using an Antek 05T200) is built into the "tub", along with the electrolytic caps, choke and power switch and fuse, and the little green LED on the front. The amplifier circuit is all on the lid, and is connected to the PSU with a six wire "umbilical" This was designed and built so that I could try other amplifier designs on the existing PSU, with a minimum of wasted efforts. OPTs are the Triode TF103-48s, 5K to 8 ohms. Good for about 1.6WPC and sounds quite nice.
The circuit design is essentially identical to the "Darling" except for the tubes used. 12DT8 is equivalent to 12AT7, except that the filament is not center-tapped. Cheap tube, as it is not (yet) "audiophile approved"
/ed B