The largest reduction in the noise floor I've ever perceived in my many systems over the past 40+ years occurred about 3 years ago when I first substituted a class D amp in my system after using class A/B amps for virtually my entire home audio life.
In retrospect, there have been many changes in my sources (vinyl to cds to Super Beta Audio recordings of my cds to DVD-A and SACD to my current computer audio with ripped cds and 24 bit/96khz downloaded files) and many changes in my speakers (no-name Pacific Stereo to Klipsch Heresy to Mirage to Maggie IIB with single sub to my current Maggie 2.7qr with 4 subs) but relatively few changes in amps (from Pioneer and Yamaha am/fm receivers to Adcom separates to various mid-level class A/B amps with a VTL tube preamp to class D stereo amps to my current D-Sonic class D mono-blocks).
Without any doubt, the change from class A/B amps to class D amps in my system resulted in the biggest perceived lowering of my system's noise floor of any system changes I've ever made. I was not expecting this dramatic perceived noise floor lowering with the switch from class A/B to D amps since I didn't recall it being mentioned by others who had switched to class D amps.
I did immediately notice other changes to the sound of class D that others had mentioned such as increased bass response, increased dynamics and a detailed but smooth mid-range and treble response comparable to good class A/B amps. But the lowered noise floor, that made it seem like the music was emerging from a dead calm inky blackness, was just a big bonus that made all my familiar music sound even better. I also think this lowered noise floor enabled my system to sound more detailed.
Given these results with a class D stereo amp, I subsequently bought another stereo and a pair of mono-block class D amps to replace the remaining class A/B amps in my combo ht and 2-ch music system which has increased the performance of both.
For what it's worth,
Tim
In retrospect, there have been many changes in my sources (vinyl to cds to Super Beta Audio recordings of my cds to DVD-A and SACD to my current computer audio with ripped cds and 24 bit/96khz downloaded files) and many changes in my speakers (no-name Pacific Stereo to Klipsch Heresy to Mirage to Maggie IIB with single sub to my current Maggie 2.7qr with 4 subs) but relatively few changes in amps (from Pioneer and Yamaha am/fm receivers to Adcom separates to various mid-level class A/B amps with a VTL tube preamp to class D stereo amps to my current D-Sonic class D mono-blocks).
Without any doubt, the change from class A/B amps to class D amps in my system resulted in the biggest perceived lowering of my system's noise floor of any system changes I've ever made. I was not expecting this dramatic perceived noise floor lowering with the switch from class A/B to D amps since I didn't recall it being mentioned by others who had switched to class D amps.
I did immediately notice other changes to the sound of class D that others had mentioned such as increased bass response, increased dynamics and a detailed but smooth mid-range and treble response comparable to good class A/B amps. But the lowered noise floor, that made it seem like the music was emerging from a dead calm inky blackness, was just a big bonus that made all my familiar music sound even better. I also think this lowered noise floor enabled my system to sound more detailed.
Given these results with a class D stereo amp, I subsequently bought another stereo and a pair of mono-block class D amps to replace the remaining class A/B amps in my combo ht and 2-ch music system which has increased the performance of both.
For what it's worth,
Tim