I like both speakers. The Dynaco's sound musical with any associated equipment. The Heresy's are very transparent but require careful matching (they like tubes) and they can sound lean in the bass. Neither is noted for great bass like the large Advent was. Polk Monitor 10s can rock and have plenty o' bass.
If I had $800 for used full range used speakers I would look at Spendor, IMF, B&W, ADS. You could also get new Magnepan MMGs in you budget range.
If I had $800 for used full range used speakers I would look at Spendor, IMF, B&W, ADS. You could also get new Magnepan MMGs in you budget range.