Class D amplifier with TPA 3250 board

Folks on another forum I shall not name seem to heavily imply that all amplifiers should sound the same (or very similar). They rave about these cheap tiny Topping/Aiyima amplifiers with class D TPA 3250 amplifier boards. These same boards are used in Genelec active monitors, so they must be good? I'm flustered because there no direct comparisons between these TPA 32xx amplifiers and more conventional/expensive branded amplifiers. The same folks on the forum I shall not name imply that I'm a dunce for spending so much money on a tube amplifier (quote: it's a distortion factory and it can't play grindcore metal music so it sucks).

@kokakolia Tube amps can play grindcore just fine!

Since this is a buzz (not a hum, hum in France would be 50Hz only; since you have 100Hz you probably also have artifacts you can hear in the tweeters) and not a hiss there may be things you can do.

The first thing to do is find out if, when you short the amplifier's inputs, does the amp still make the sound?

Or does it only make it when the amp has something connected to its inputs?

If you can answer those questions we might be able to make some progress without any serious investment.

With regards to the TPA3250 and other chip-based class D amps, I think if you look at their specs you'll (and those over at ASR) you'll be surprised to find their distortion at full output is about 10%, more than your tube amp! I've got the Topping amp (the little '30 Watt' unit) and its quite boring to listen to- almost to make you think that specs are more important than the music 😁  Which they are not.

You need good specs to get the music right and plain and simple, while those chip based class D amps do some things fairly well, their specs suck. This is not to say class D does not work! But chip based class D amps don't represent the class of operation...

So answer my questions above and let's see if progress can be made.

Alright, so I do not have the amplifier with me.

The amplifier always made that hum, even on the shorted inputs. I only use 1 out of 4 inputs so it's quick to find out. The hiss is gone. 

But the amplifier is currently in repair. The artisan told me that he was gonna add diodes to convert the AC current into DC and that should kill the hum. He told me the hum was 100 Hz. 

From memory, the hum was just annoying enough to ruin quieter songs and unnoticeable on busy songs. But I love Billie Eilish and her tracks are equal parts quiet and loud, so you notice the hum. So I really hope it's the AC current killing the vibe with the hum. 

Anyways I can't do anything until Sunday. 

@kokakolia most likely place would be eBay

Trends TA10.1, Amptastic Mini1, there are plenty of others like the Bantam Gold (a bit more expensive)

You could also experiment with the other Chinese stuff, like SMSL, Topping, Aiyma - they sound good and powerful and lively but there is slightly less attention to passive components making them a little bit less refined sounding. Still, great little amps for not much money. I live in Belgium, by the way. ;-)

I also order a LOT from AliExpress if you can't find what you want on Amazon or eBay, and I never had any issue so far (choose the right vendor with plenty of good reviews)

@atmasphere I'm not familiar with the Topping amps but, aside from the Trends and Breeze Audio used in my main system, I own a few SMSL cheapies and I don't find them boring sounding. YMMV of course, and they certainly aren't as good and refined as the Trends or Amptastic - they do provide more power tho. They are best used with sensitive speakers and well within their limitations, and the ones that allow for input potentiometer bypass benefit from a good full size preamp. They also respond very well to a better non SMPS power supply. But yeah obviously they won't provide the euphonic sound of a good tube amp.

@rolox My curiosity peaked and I bought the Sure amplifier with the Tripath TA2024 chip. Some reviewer online compared the Sure amplifier with the Amptastic and the Trends and stated that the differences were pretty negligible. Since the Sure is 60€ (total 80,8€ with power supply and shipping) on sound imports VS 280€ for the Trends, the choice was easy. 

I am more worried about the noise floor at this point. And 80€ is the price of drinking/dining/clubbing for night in Paris anyways.