Would a Pass Aleph 5 be able to drive Thiel 3.5 ?

Of course your room and desired volume level are paramount in this regard. Your pre-amp out put should be considered too. Thiel recommended 50-250 watts (as rated into 8 Ohms). As they are a steady 4 Ohm load I prefer to think in terms of 100-500 Watts into 4 Ohms. The 3.5's use and equalizer to bolster bass response. This can put an added burden or your amplifier. The answer to your question is yes but more power would be better. I would recommend at least 200 Watts into 4 Ohms. By the way, I think Pass would sound very nice with these Thiels, but some of the early Pass amps were not suited to this steady 4 Ohm load. Rumour has it that the 3.5's were designed around the then top of the line Threshold gear (earlier Nelson Pass designs). You may be on the right track but proceed with caution.

With all due respect to Audiomax while the Pinius SA-100 might be a good choice with the Thiel CS 3.5's I don't think that the two Bryston amps lack the current any more so than the Plinius might. All would be at the very least adequate. In fact the Bryston 3B is probably very very close to the Plinius in this regard. I'm not so sure about the Aleph 5, but my guess would be that it too can handle the load.