They are very different inside - and frankly, I don't hear much resemblance with the real 660. Not a bad compressor at all, don't get me wrong, but nothing like a 660.
Yeah I don't hear much similarities either, with me prefering the ear on most occassions.
What differences are there exactly? Not sure how the circuit works on the ear. I know they're his own designed transformers and PCC189 triodes