All... my initial report out of the Atma-Sphere-D compared to my Coincident Frankenstein Mk-2 300B amps. I listened for 11 hours yesterday deep into the night using a pattern of 2 hours between swapping then repeat. One thing to remember is in my system these amps are only driving my mid/high horns so from 300Hz to 21kHz thus I cannot speak to low frequency performance.
I generally listen to blues and classic rock so Etta James, The Commitments, BB King, Marsha Ball, Boney James, Diana Krall, Greg Porter, Eagles, Joe Walsh, Lenny Kravits, Los Lobos, Prince, Stevie Ray Vaughn, Van Morrison, 38 Special, ACDC, Beck, Boston, Chicago, Etc.
The AP-D frankly sounded very good and has a number of strengths as compared to my Frankies. First and foremost, the grip they had on my speakers was immediately apparent with mush improved transients and leading-edge crispness. High frequencies are clean and extended without being sharp and had more energy than my Frankies but the surprise for me was the increased power in the lower midrange to the point where I had to adjust my miniDSP xover for my LF amp to dial down the output curve in the 200Hz to 950Hz range. Of special note is the APD amps are dead quite even with my 112dD efficient horns.
The downside was that the 300B Frankies spanked the APD in the midrange as one would expect since this is the strength of 300Bs with a fuller more textured presentation with bloom and air. While the APD had good soundstage depth & width again the 300B Frankies are king of the road here as well.
In summary: I think the APD is much more accurate than the Frankies and would accel in most any system and I suspect they have authoritive base given the additional low extension power they provided with my mid-high horns. As for me, I think I may have been in the 300B world too long to walk away from the luscious midrange even with their shortcomings in ultimate accuracy. Special thanks to my dealer Koby at HiFi Logic in NJ for his flexibility for working me in.
The Atma-Sphere D's are in good company with the FirstWatt F7, FirstWatt SIT3, Cary 805C, PS-Audio M700, Benchmark AHB2 that have challenged the Frankies. I will continue to search from time to time for a suitable solid-state tube amp replacement.
