A couple friends from our audio club were over yesterday comparing the First Watt and Audio Research amplifiers. Well one preferred the FW and the other the ARC. I am neutral although maybe leaning towards the FW. The one who liked the ARC better is an Audio Research fan/owner from way back, so his heart was with ARC from the get go... and he really liked the VT50.
We all came to a definitely consensuses however that they are both pretty spectacular and fairly close. The ARC may have a little more "air" around it, especially in the highs while the FW probably has a fuller mid range and female vocals especially are startling good. Mid base very much favored the FW. Especially on a Fiona Joy SACD where the lower piano notes just had a more solid bottom residence. And the FW has probably a better and more stable image. Both are extremely good in this regards.
The ARC definitely has more power, but both are able to drive my MC's (which should be a very hard to drive speaker, 85 db, 4 ohm) to very high levels. Honestly, it is a really good problem to have

, and a very nice change of pace in amplifiers...