Of having more support power in form offilament and plate dissipation, I have another addition:Build a gain/PI stage capable oh higher output power than the finals.
I had a few folks over for some listening and one brought an EL84 amp. Nice little amp it was. Soooo, a possible for the PP2A3 amp, a differential front end built with resistive loaded EL-84/6Pi14/7189. The pentode front end has potential to deliver more power than the finals it's driving...heh-heh-heh! So it must be a good idea.
The Russian SV83 or the 6Pi15 are other alternatives, pref. given to the SV83 if it is still available. We'll be running a lower g2 voltage than is typical of AB1 U-L designs so it ought to last a long time. Make g2 about 1/3-1/4 the anode voltage and adjust to taste. The g2 will determine what part of the plate curves the straight load line will go. As always for pentodes, this is quite important for best sonics and distortion spectra.
cheers,
Douglas