[Driving these AR3a speakers]

" the Pioneer amp can be safely used to power 2 paralleled sets of 3a’s"

I know we are in the hazards of following an ancient post, but note please the key detail above in the OP's posts is that he blew two AR 3A drivers (likely woofers) in trying to drive 2 paralleled sets of 3as at less than 4 ohms.  Several people, and I, recommended using a power amp rated for loads of less than 4 ohms; he showed up here because someone had already told him it was likely fine to use a vintage class A in this labor, and that experiment spectacularly did not work.  Empirically, based on my experience of several class A amps (rated at 70 watts at 4 ohms) getting hot driving 3As, I don't think it is a good idea, and I'd rather play it safe with a class D power amp; if someone can drive a Sherwood at 1 ohm as you say, good for you.

[Driving these AR3a speakers]

For others interested in this issue (the demands of the great-sounding but low-efficiency 3a), I recommend class D power amps for AR 3as; class D amps can drive 2 ohm loads and generate a tiny amount of the heat (undetectable heat in my use--I can't tell to the touch that this NAD C268 is generating any heat) that a vintage class A amp can.  3As as a single pair can demand loads of under 4 ohms, even 2 ohms intermittently, and a vintage class-A (rated safe for 4 ohm loads) confronted with that work can get fry-an-egg-near-the-heat-sinks hot: not good, stop, change course.  I still use a vintage amp (a Sansui 999) as a pre-amp and control surface (it was designed with the ability to uncouple its power stage), and class D power amp.  Until I got 3As, I didn't know much about class D amps.  One can investigate them in detail at audiosciencereview dot com.

[AR 10" woofer (2ax & 5) specs?]

I am curious iabout the ohm rating of AR 2ax woofers, and that of the AR 5 woofer (independent of the system, which I know is 8 ohm in each case) .  Are the relative  woofer ohm ratings the same?  I know the materials, design and engineering of the 2ax and 5 woofers differ, but could a cloth 2ax woofer work in an LST-2 enclosure, which used a 5 woofer? Fairly deep trivia,  but I bet somebody here may know.