The Future of Audio Amplification

While I have a dedicated listening room I built 25 years ago, I made some major errors in construction.  It is good that it has a 6" rebar reinforced slab, 8" plates with staggered 6" studs every 8".  Survived a 6.9 earthquake with no damage (or to the rest of house).  However, I also made it vaulted from 8' to 11'6", have large multi-pane wood casement windows along both long walls and behind the speakers and dual layers of screw attached, non-staggered jointed 5/8X drywall on walls and single layer on ceiling.  Also, the room designed to have 25,000 records now has 42,000 records.  I was able to tweak the acoustics to sound very good.  Without treatment, slap echo galore but definitely no problem with sound in or out of the room.

In 2 months, I'm moving to another home and will convert 2 of 4 oversized garages dedicated as a sound room.  No windows, flat high ceiling, superior insulation   Sure, it's 40% smaller space but at least it will be dedicated to sound only and built better for it than in 1993.  The records/cds will be stored in the adjacent room.  We will have a large family room for video and a small audio system in the large living room.  I would have built a dedicated larger listening room but for the 2017 City of LA law cutting in half the floor area ratio. 

That small living room system has a small high end CD player, really small sub-miniature tube pre-amp and a voltage regulated (non-ultralinear) redesigned Dynaco ST70.  Fits on a small rack.  Almost like a streaming setup size.  Only the speakers are medium size Legacy Signature IIIs.

IMHO, the underlying question to the future of class D is:

Who is going to buy super exotic (expensive) USED amplifiers? Recalling the TAS March 2016 review of my Audio Alchemy stereo amp and dac/pre @ was $1995 each. The reviewer, Robert Harley (gave them Editors Choice Award)  compared their sound to the Soulution amp/pre which I think was priced near $60,000: the reviewer  noted that both were designed by Peter Madnik, and that the AA components were not sonically that far off of the uber expensive, and highly praised Soulution components 

Here's a great quote from erik in his AudioGon class D thread:  "Sighted or blind, I cannot hear a difference between them an Parasound A23s. None. Zero. Nada."

Now I owned Parasound A 23, several W4S stereo/mono/ multi channel amps, Emerald Physics 100.2 SE monos and now my Audio Alchemy stereo amp, and I can definitely hear the generational improvements, and the AA (apparently with HypeX modules) stands way above those that I owed. The AA amp had considerably more wallop than the 4xs as expensive (MSRP) EPs, which can often be ha for ~$2000 the pair these days 

Snippet from Stereophile August 2016 (according to review the stereo amp is essentially the same topology as the monos):

"Madnick told me that, inside the DPA-1M, the signal is fed to a differential pair of JFETs feeding a low-power MOSFET driver stage. The circuit is servo-controlled to cancel any offset and to avoid having to use coupling capacitors in the signal path. This input circuit is powered by a dedicated power supply with ultra-low-noise voltage regulators. The class-D Hypex output module is powered from a switching power supply. The DPA-1M is a bridged design, which Madnick considers "the best-sounding way to do it." Of course, the sonic characteristics of the DPA-1M depend not only on its circuit topologies, but on the choice of specific components, PCB layout, and fabrication materials, as well as the selection of internal wiring and, one assumes, various proprietary factors. 

There was certainly nothing about the sound that screamed "class-D." In fact, had I been told that I was listening to a high-power class-AB amplifier—the kind that would require the help of a friend to lift it—I would have had no reason to doubt the truth of that statement.

Theta comparison;  And so, in a more modest way dictated by its price, is the DPA-1M. Like the Prometheus, it produced no artifacts, and added none of the "clinical" sound for which class-D amplifiers are often criticized. (FURTHER >80% OF THE SONIC GOODNESS AT 1/3 THE PRICE!)"

So, whereas the older class D left many of us wanting, the current and near future of class D is such (IMHO) that people who own uber expensive A/AB amps will already have a hard time getting pennies on the dollar

Read more at https://www.stereophile.com/content/audio-alchemy-dpa-1m-monoblock-power-amplifier-page-2#X4UzH1ZEC5...
Read more at https://www.stereophile.com/content/audio-alchemy-dpa-1m-monoblock-power-amplifier#DaPTJ23tBl4br8kO....

The Tad Evolution class D amps specs quote 1% distortion. I believe most amp designers look to minimize distortion, and I’m sure TAD does as well. I use Spectral and am happy with the lack of distortion,incredible dynamics,nuance,faithfulness to the waveform(read music) and emotional connection this allows. I’m surprised that some argue Class D is equivalent; but we all hear differently and have different sensitivity to distortion. As I listen to live music often; my ear is sensitive to sounds that don’t reflect live. One poster mentioned he found “live” music flat and boring. Obviously there are positions for everyone. If one grows up listening to mp3 perhaps they’ll gravitate to that for a lifetime? I can’t imagine it though. 

John Atkinson measured PS Audio's M700 monoblocks ability to produce 700 watts at 1%, and over 100 watts at 0.005%, both figures into 4 Ohms at 1K. At 30 watts into 4 Ohms, which many of us never exceed at normal listening levels, that number fell to 0.002%. From 20 to 20K at 20V, that number never rose above 0.2% into 4 Ohms; the figures were better into 8 Ohms. Not that distortion tells but a part of the story, is something not to worry about with well-designed Class D amplification.