Hi "d.c.",
Yah, I've fooled around with a few of those amps, along with a few different speakers.
My Altec 19's ran 'happy' with that original little Sonic Impact, that I still own. Right now, it got parked at my wife's computer work station firing the speakers for her audio there.
I've also got a Teac that got modded work with batteries that jams pretty well also on the 19's.
I have several sets of high sensitivity speakers around here I've dinked with enough to marvel at how well the SI and Teac play.
I haven't tried the SI with the Hornshoppe Horns I've got, but now you have me thinking to try it.
If you ever want a listening session before plunking down money, and don't mind driving as far as into Illinois in Collinsville, shoot me a p/m and we can set something up.
I might have to buy one of those SI version two models just to see how it plays. For those prices, one can afford to have them laying around 'the stable' for tinkering.
Certainly it is a direction worth investigating, if you have the inclination.
Best Regards!
DeadFish