The 7900 is made by ATI and they have been the OEM for amps offered by a number of companies including Outlaw. ATI has a solid reputation. Is the 7220 built by ATI? If so, I don't think you'd go wrong with either. The real questions are: What kind of speakers will be driven by the amp and how much headroom is desired. FYI, a Class D amp can achieve the same power without literally hurting your back and uses less energy than the typical Class A/B. ATI makes a couple of them.
Outlaw 976 | ATI 2005 | M&K 850s Left, Center & Right, Surround-55s, MX-70B Sub | Harmony 950 remote | Panamax 5100 | OPPO UDP-203 | LG OLED55B7