Yes, Tony, they did. ILP paid around 3 a pair as they had (maybe still

I'm rather impressed. Their amps are better than I thought then.
Those particular hitachi fet's were some of only a few types
specifically characterised for audio use, and they gave much better
audio performance than other similar devices. Provided they stuck
to something similar to the Hitachi reference circuit from the
hitachi power fet app note the audio performance would have been
excellent. Shame I never got my hands on one of those MOS modules.

This was mass production for a world-wide market.

I didn't know ILP were that big. Certainly the robustness of the
amps I used was without question, they stood up to tons of abuse.

And searching on google reveals - they're still going!

link: www.ilpelectronics.com.

There's an archive where I found the original data sheets for
the HY50 and HY5.

Tony