GTP, you're thinking, but you've overlooked one(well-buried)point: the zone 2 line out only outputs analog source material, so it wouldn't be usable for most purposes with your main M22s.
Also, keep in mind that you can't just "give" speakers more power; they take only what they need for a given sound output level. It's likely that your 605 already has plenty of output capacity. If the protective circuits of the 605 aren't shutting it down, the heat level is still within specified limits and shouldn't be a major cause for concern.
