I'm glad you're liking it - I love sharing the information, that I have managed to collect, with others.
One thing I should have noted as an add-on to the Hughes AK-100 review: Its lower priced 'brother', the Hughes AK-500 Retriever, employed an analog IC developed and manufactured by Hughes Audio Division. It was a large-scale analog chip that was more of a prototype than something they actually meant to market and sell in large quantities. The SRS process originally started development as a system for use by passenger airlines to improve the sound of in-flight movies and music on those cheap airplane headphones; after the rave reviews the AK-100 unit got among audiophile magazines like The Perfect Vision and The Absolute Sound, Hughes knew they had a good thing with SRS - but the discrete circuit was very complex, so they quickly developed the SRS system as analog chip to be incorporated into new or upgraded airline audio systems. There were no airline takers, so the chip got re-purposed for the home market in the low cost AK-500. Unfortunately, the chip had some problems and under certain conditions, with certain music, could have audible high frequency noise or audible level shifts of the L-R servos. That's why Hughes had Sony design an SRS chip for the mass market - they felt Sony could do a better job. The Hughes AK-100, which was the first on the market, was built entirely from discrete components, and didn't suffer any of those problems. It continued to sell well with one company, Audio by Van Alstine inc, offering modified AK-100's with better performing op amps and better spec'd resistors & capacitors. Since the AK-100 kept selling so well, the AK-500 quickly got closed out for less than $100 after a short time. That's how I ended up buying mine, from an ad in the back of Audio magazine - a place called Stereo City had the AK-500's for $79 and I thought I'd try it out. I loved the SRS system and quickly bought another for my bedroom stereo. I've never heard the AK-500 misbehave in the ways that Hughes said the unit could; it's always performed perfectly, so if someone runs across the AK-500 at a good price, go for it - it sounds great but doesn't offer the neat display that the AK-100 had. The actual SRS processing performance is exactly the same between the two units.
In the late 90's the NuReality company offered a large home SRS unit that had a display 'similar' to the original Hughes unit, but unfortunately, it uses, like all modern SRS units, the 'non-servo'd' SRS system that doesn't offer anywhere near the performance of the original Hughes units.
