Is the Hegel H-20 better than the Parasound A-21?

I attended the 2013 NY Audio Show and I agree with Audiooracle's description of the Aragon 8008 sound. The room featuring this amp had lots of people visiting multiple times. That room, along with the Martin Logan/Krell room, had the best sound by far on that floor. The sound performance easily surpasses the price tag of this amp and the entire system. The rest of the system was the Neo-Classic 300B RC Preamplifier, Waterfall's Victoria Evo glass speakers with Wireworld 7 cables.

AudioZen, that's not the complete story. Acurus and Aragon's parent company was Mondial. Mondial was sold to the Klipsch Group in 2001 and they never did anything with the brands. Rick Santiago left Klipsch and founded Indy Audio Labs, which acquired Aragon and Acurus from the Klipsch Group. The brands were dormant for years, but it seems that the person leading the two brands now has always been involved with these amps.

AudioZen, other than I could not get a very clear picture of where the instruments were placed in the soundstage (like I get in my system), I didn't detect any of the symptoms you described. I would say the sound had some warmth, although it was most likely due to the tube preamp the 8008 was paired with. The sound was as crystal clear as the much more expensive ML/Krell room.

The only thing that raised a flag is this statement from the 8008 manual:

2. Using higher-efficiency loudspeakers (87dB/W/m or greater) will reduce the average amount of amplifier power consumed to produce a target listening loud-ness. This effectively helps reserve greater peak amplifier power when loud musical transient passages are reproduced.

This value seems to be at the threshold level of Magnepan speakers (86dB/500Hz /2.83v) and other low sensitivity speakers. So, I wonder if the amp is stable below 4ohms.

You are not understanding what the manual is saying

Oh, I do understand what the manual is saying. I raised a very valid point: is this amp stable below 4 ohms? You should know that 4ohms is not an absolute fixed value.

they are saying that the amount of electricity consumed with lower sensitivity speakers will increase

This is just common sense.

and this amplifier is a beast based on original Krell Class Designs, think KSA 250, the amp was designed by Dan D'agostino originally and has no problem with less efficient speakers

This is irrelevant concerning the 8008 amp's behavior since they are not the same design.