My APL Denon 3910 has well over 200 hours on it, and without question it continues to improve. I have auditioned it in direct connect mode, as well as playing through my modified Conrad Johnson PV-12 tube preamp, and much prefer the direct connect. There may be slightly more "bloom" with the CJ in the loop, but when directly connected to my Spectron amp, the improvement in soundstage, imaging, transparency, ambience and overall musicality is dramatic.
I recently installed the new Spectron Musician III Class D amp (600 wpc)in my system, and all of the above improvements wratched up another notch, plus adding a much more life-like tonality. I will be doing a review of the Spectron digital amp shortly. It is a superb match for direct connecting the APL Denon.