Art, your 3470 likely would have a 4 ohm rating of about 150 watts. Specifically on the published 100 to 120 watt difference at 8 ohms, however, the difference between 100 watts and 120 watts is only about 0.8dB(e.g. 110dB on a brief peak compared to 110.8dB). It's highly unlikely that this would ever be of significance in your listening since you've probably got a fair amount of headroom left on your 3470 now, and unused headroom is just that; unused. Although that does look like a terrific price on the 3480, maybe you should have resisted.
I'd like to suggest an alternative for some of that $259 which will make a real difference in your enjoyment. I know that you like classical CDs, so why not add a bunch more? For example, Tower Records now has a sale on Naxos for $5.99 with free shipping. I know of at least a dozen that I bet you'd love.
