So... you just mashed some cereal rice with amylase, 3# to a gallon and got 1.055 wort? How many gallons of wort did you get out of that, before reducing to syrup? I know that when I boil rice to eat the rice soaks up crazy amounts of water; if that were happening I'd think a quick simple sparge would really help out. If we assume it's 70% fermentable, that's about double the gravity needed for a "standard" strength beer (not that homebrewers tend to go that low-gravity ). Assuming 70% fermentable, that'd be 7-8# of rice for a 5 gallon, 5-ish% ABV brew.
I know that simply mashing whole rice has been discussed before, and while I think the discussions were mostly hypothetical, IIRC the potential problems people came up with were the germ and oil content. Did you notice any signs of excess oil in/on your wort? If so did it skim off easily?
Now I'm thinking about this a little more. If we were to steep some rice at lauter/sparge (long grain) or mash (short grain) temps for a while to gelatinize the starches, and then just mash with exogenous enzymes, how would that turn out?
Now you've got me tempted to do my next brew with this sort-of-but-not-really cereal mash of rice, dumping in some oat malt with the enzymes... this may renew my interest in making some buckwheat crystal malt to toss in, even though malting is a royal pain in the ass...