Class D at low volume


How do class D amps behave at low volume levels?  My question is general rather than related to a particular amp.  I know there are exceptions, but as a rule, SET’s and class A SS excel at low volume.  What about class D?  Is low volume performance of class D predetermined, all else being equal? Do class D amps have a comfort zone?  Do they distort more at low volume or is it uniform throughout?  For the purpose of this question I am only referring to analog input amps and not the ones that take in PCM (e.g. NAD M2).

The second part of my question is as follows.  I’m interested in some higher end commercial class D amps from the likes of lab.gruppen, powersoft, mc2, XTA, etc. due to their network-ability as in, I can control them, DSP them, and stream digital, all via RJ45, at the same time dispensing with all the extra boxes and cables.  But, they are all of very high power from 100‘s to 1000‘s of watts.  Does this mean that in a domestic setting at low volume they operate much closer to their noise floor or is this different with class D?

Pavpet, happily replacing an expensive SET with a much more modest cost Class D amp is certainly saying a lot. I've heard both sounding their best and frankly Class D technology is a game changer for me when it comes to considering tube amplification. I just like good sound when I hear it no matter how it is made.
You guys already know how I feel about Class won't find another owner out there happier than me with the Peachtree Grand Integrated X-1. And for people who not only need to listen at lower volumes, but do so in smaller environments, the lower heat output of Class D sure is welcome when you're not sitting that far from the device. I'm in Arizona - last thing I need in July is to have the AC fighting my amplifier.
I caution against comparing tube, linear solid state, and switching amplifiers. Each has its own set of virtues that the others can't quite match and that class D is simply a third choice in amplification. On the other hand reading about the Bob Carver challenge gives one pause.

Assuming that everything in the chain contributes, in my experience low volume dynamics is more a function of the speaker design. Most of the contributors above have evolved with class D. For me beginning with the PS Audio HCA-2 a few others then the NuForce SE class D has been the most responsive to power and cabling. The nCore 400s are another step forward that I can only describe as more of everything which would make the NC1200 yet another level that is better described by Larry Greenhill in his Theta Prometheus review of the Hypex 1200s ability to handle high rail voltage.
I've been into high end audio since 1970,and these class d amps wyred for sound and nuprime/nuforce are killing my very expensive WYETECH ruby

I agree with the previous repliers that the class D amps I've used perform very well at low to high volumes. In fact, this was one of the characteristics I was pleasantly surprised with when I installed my first class D amp in my system, a ClassD Audio SDS440-CS amp; I quickly noticed that the full frequency range, from deepest bass to highest highs and all frequencies in between, was presented in proper perspective no matter what level I played back at. This was a revelation to me. My prior amp was a class A/B Aragon 4004 that outputted about the same power (400 w into 4ohm speakers) but was many times larger, heavier and hotter. I would typically play music at high volume, with the Aragon, to attain what I considered to be the proper frequency response from bass through treble. I quickly realized the class D amp was different; the frequency response was well balanced at low volumes up to extremely high volumes. My wife was actually the first to notice I was playing my music back at a somewhat lower volume with the new ClassD Audio amp.

This issue reminds me of the 'Loudness Controls' found on receivers back in the 1970's and 1980's, which boosted the bass and treble when listening at lower volume levels to compensate for their perceived absence at lower listening levels. In my opinion, the class D amps that I've heard have no need for loudness controls since they maintain a proper frequency range perspective no matter what volume level is chosen. I'm not suggesting these amps boost the bass and treble, just that they get it right somehow.

I am not an audio engineer but I have a theory why class D amps seem to have such good frequency response that maintains proper perspective at various volume levels:

It's my understanding that class D power conversion modules typically use high levels of global feedback. The input signal is constantly being compared to the output signal (thousands of times per second) prior to the output signal being amplified. The output signal is only sent to be amplified once it matches the input signal and any necessary adjustments have been made. This high level of global feedback, which designers of more traditional amp topologies typically try to avoid at all costs, is a mainstay of class D amp design. My theory is that this high reliance on high levels of global feedback is responsible for class D amps' astounding neutrality and their performing so close to the ideal of 'a straight wire with gain'. Also, my theory is that this design results in excellent frequency response at all volume levels.

As I've stated I have no technical training on amplifier design or electronics. The above is based on personal reading about class D amplification combined with any small amount of rational thought and common sense I may possess. I may have this entirely wrong, however, and would welcome comments and thoughts on my theory from those with more technical knowledge on class D amps than myself.

Regardless of my theory, I do own 3 class D amps (D-Sonic M600-M mono-blocs, a stereo ClassD audio SDS-440CS and a stereo Emerald Physics EP100.2SE operated in bridged mono configuration) and can confirm that all perform very well at all volume levels as unanimously reported from others thus far.

I would suggest you won't be disappointed, especially considering many class D amp sellers offer in-home trial periods to ensure your satisfaction.

Good luck,