HT input anomaly on Grounded Grid Preamp

Recently, I completed building a Transcendent Sound preamp, with a home theater input. It was confirmed as being wired correctly by Bruce at Transcendent.

However, with the HT inputs in use, all the other inputs were nearly muted, and instead of having unity gain, the attenuator had to be turned up to use the HT input.

I have since been using a normal input for HT, and have converted the HT input to an output, for my subwoofers.

No one has been able to puzzle out this issue, from the preamp's designer, to John Chapman at Bent Audio, or anyone else so far. I know it's not much info, but I'll supply what info I can. Anyone care to take a crack at it?

Thanks and regards,
Dan