It would be very difficult to narrow down to even a top 50 or 100. There are simply so many quality, integrated amplifiers out there made in the last 40+ years.
The OP appears to have a noise issue which apparently is 'solved' by going balanced. Using an input topology to solve a problem instead of curing the issue is a band aid approach IMO.
These hyped class D amplifier designers are very clever by extolling what they see as virtues and conveniently ignoring, dismissing, or failing to specify parameters that have for decades defined the very essence of high fidelity amplification.
The focus seems to be on biggish power numbers, but power at rated distortion levels that are a complete joke. Consider the n-core specifies its (headlined) maximum output at 1% THD. No amplifier, aspiring to High Fidelity pretensions since the 1950s would have dared printed such a hideous number. That is the realm of the bad old days of ghetto blasters and car stereos.
Harold Leak specified point one (0.1%) as the point where HiFi started in
1958 with his tube gear. 1958! It's only at half power numbers where these Class D modules approach THD levels that have been common in Class AB amplifiers for many decades.
As an example let's take the "
NC500 OEM Definitive performance class D amp" with "
its measured and sonic performance (that)
actually raises the bar for audio amplifiers of any description."
The headline numbers are:
View attachment 19245
Let's look at their own measured AP THD vs Po:
View attachment 19246
I have several amplifiers and power amplifiers where the ratings were XXX watts per channel from 20-20KHz, at any power from 250mW to rated power output and THD of less than 0.003% or similar.
Based on this AP graph, the amplifier module would be a 200W@8ohm (not a 400W@8ohm) module at similar distortion levels to a typical high performance 35 year old power amplifier. Proper HiFi manufacturers didn't specify their headline numbers halfway up the skyward exponential trajectory of their THD curve!
Let's look at FR.
I have plenty of amplifiers with small signal frequency responses out to 200KHz+, many over 300KHz and some up to 600KHz. They are
ruler flat within the audible bandwidth, above and below.
The NC500 by their own FR plot is half a dB down at 20KHz at a measly 1 watt. Ask yourself, is that really '
raising the bar'? Clearly, the bar is drooping rapidly, and in the audible bandwidth too.
View attachment 19247
Anyway, I want to see some scope shots of square waves on these things driven into capacitive and reactive loads.
I want to see expanded FR plots that go from DC to 50Khz with tight deviations.
I want to see overload recovery plots.
I want to see proper FTC style, soak testing then full power testing as per the guidelines, not short term peak power, pretend numbers.