Sorry I've been away from this thread for a while; we had a quarterly board meeting recently which put me behind the 8-ball for the better part of two weeks between preparation and decompression/catch-up.
Regarding 4 subwoofers, we've tried dual AS-EQ1 vs. one AS-EQ1 with Y splitters. Frankly the single unit with Y splitters gets a comprehensive look at how all four subwoofers interact in the room when pinged at the same time, which is an advantage over dual units each running just two subs. In that regard, I consider it a superior solution to dual AS-EQ1.
We've also determined that if you are going to run quad subs with one AS-EQ1, the results will be better when each pair of subs are on adjacent walls and not opposite walls.
Regarding MAC users, this is straight from the Audyssey SubEQ code team: "We do not support emulators of Windows. Both MultEQ Pro and SubEQ applications only support Windows XP (32-bit), Windows Vista (32-bit). Bootcamp is allowed when XP or Vista (32 bit) is used. But no emulators of Windows (such as Parallels) are supported. They are not tested and should never be used in the field."
Regarding balanced I/O: As others have already stated, we inquired about them early in the development process. They were not a hardware option at the time on the Audyssey external Pro box, on which the AS-EQ1 is based. So the idea was nixed early on. The overwhelming majority of our customers use RCA interconnects, but there remains a small (yet exceedingly vocal) group of balanced users. They can either use a passive adapter (which unbalances the interconnect), or an active unbalanced/balanced converter (like the Behringer unit previously hotlinked) for about $100.
Regarding the Audyssey Subwooofer Equalizer, it is identical in all respects (indeed they are made side-by-side) to the AS-EQ1, except that it is designed to accept the Pro mic from the Installer Kit.
Regarding the differences between the AS-EQ1 and consumer AVRs with MultEQ XT - the AS-EQ1 has more processing power, greater filter resolution, and more sophisticated algorithms. Customers can/will hear an improvement in the bass quality with the AS-EQ1 over a consumer AVR with MultEQ XT. It can also handle dual subs of course. Whether these improvements/advantages are worth the asking price is up to each enthusiasts to decide. We are sold out of the first production run, and have already pre-sold a good portion of the second production run, and early reports from overseas users are all exceedingly positive. So it appears we've struck a chord with this product with respect to price/performance ratio.
If I missed any recent issues, let me know; I'll try to keep a closer watch on this thread.
Director - Technology and Customer Service
"What We Do In Life, Echoes In Eternity"