I second the recommendation to try a used Hafler power amp - my choice would be the DH-220. I got mine on eBay for $150 about four years ago - they seem a bit more now, about $200, but still well worth it. I'm sure an ST-70 would sound very good, but it will be more money, and very possibly much more hassle. Same designer, btw.
My NAD 3020 is still going strong after 30 years, and powers my wife's kitchen system now.
My NAD 3020 is still going strong after 30 years, and powers my wife's kitchen system now.