The PE's IMHO are a fairly tough load. I think they are a great speaker, but surely not an 8ohm load. An amp that drove them well for me was an Air Tight ATM-2 at 75-80 watts.
Of course the ATM-2 w/ Tamura Transformers are not your average 80 watt tube amp. The Fidelio Encore, while not as full range, is an easier load that will work w/ 60-70 watts.
Not saying the Parsifal cannot, but it will be more of an individual opinion, w/ things like room size and type of music perhaps coming in to play. Again, all this IMHO.