I'm not that familiar with Sunfire, but I quick review of the owners manual for that amp reveals a 0.5% THD. That's 10x the THD of the Denon you have now. A 70W gain from 130W is only about a 1.5db gain. You will not notice that headroom.

I would recommend going for a quality 2 channel power amp rated at least 400W per channel to get a noticeable headroom improvement. Try to get one that is in the 0.07% THD range or better.

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