There is an auction for a Symphonic line RG-1 at $800 with no reserve. I have owned 2 of these. They are OUTSTANDING amplifiers. Period. Smooth, quick, and exceptional control over drivers. IMHO leaps and bounds over the 3 you mention. 100W class A is not as "tiny" as it sounds. These amps will put out at least 65 amps of current. Mine produced almost 70 amps. i actually heard two of these with A-1's and it was a knockout! I did not like the Halo with them although a Simaudio W5 stereo sounded very good.
Jeff
Jeff