I wouldn't go any smaller than 1.5 cubic feet. Going smaller demands more from the amp as the servo system tries to maintain a linear output, and the smaller box fights harder against it to doing that.
That is why with less power then box can be bigger and with more power the box can be smaller.
The A300 does not have the rumble filter or the additional 12db per octave selectable slopes at 50Hz and 80Hz.
Danny,
Totally understand the point around power/volume ratio (and get why something like the ULW-10 had a 650W amp...)
From what you are saying, I'd be better off going with the 370PEQ in a smaller enclosure. When you say 1.5 ft^3, do you mean internal volume. I take it that you wouldn't take any more off of Brian's cabinets (15.75x15.75x17).
I have the opportunity to possibly buy a used F12G w/ an A300 amp - which is why I asked. Price is going to have be pretty good for me to jump on it vs. going the a370PEQ route...
I am a little confused by the selective slope and rumble filter. If I am using bass management from the Denon 1909, and am looking for a sharp slope after 20hz (don't want to be producing subsonic sound in an apartment), I am under the idea that I don't lose anything going with the A300 amp...