At 10Hz it is approximately .6 ohms.
That when the vinyl warp frequency will tax an amp, or even a bit of dc servo flutter when the mains chucks a slight wobbly.
It's been reported that Jim Thiel ended up using Krell 600 Watt'ers.
Correct type of amp, that will almost double down to 2ohms without breaking a sweat, though the 250 or even 150 watt'ers would do, they all can do the Krell doubling act.
There are many other brands that do the Krell doubling act also, all use Bi-Polar (bjt) output transistors, just like the Krells.
Cheers George