Class D - A Fork in the Road

Clearly, silicon based Class D amps such as Eigentakt have caught up with GanFet if not exceeded (and cheap amps like Fosi and Aiyima are not some of them).

Of course implementation matters; as it does with GanFet as well). The great thing is you can find plenty of companies where you get a good front end without paying the NAD and Marantz prices. Companies like Nord Acoustic and VTV offer a plethora of options. I really love my Nord monoblocks at half the price (or better) of any GanFet and have better specs. VTV even has a tube buffer stage option. Most of these have swappable opamps too. Much better value for money. Just avoid the cheap chifi ones. Eigentakt and Nilai are the way to go. ICE is cheaper and a little cold sounding. So I wouldn’t recommend that one.

Sadly, you won't find a purveyor of GanFET willing to go toe to toe with one of the better D amps I mentioned above. I find that telling. I've listened to them and wasn't overly impressed with any aha moments. Their claim to fame only applies to the cheaper D amps from China and the mass produced, sourced amps used for third party purposes. Bruno Putzeys has a good interview where he effectively explains his (Eigentakt) way of getting around GanFet's claim to fame of faster switching speed. So please look closer at these amps with implementation in mind. 

Here's a good place to start:

https://nordacoustics.co.uk/product-category/nord-3-purifi/9-1et9040ba/

Or

https://vtvamplifier.com/vtv-purifi-high-power-module/

I have the McIntosh MA352 which is an integrated with a tube pre and a SS amp. You see, I like to listen for a little while about 4 different times of the day. This would require me powering up and down throughout the day, or just leaving it on for about 15 hours each day, and blowing through the preamp tubes each year. So I've been considering a Class D to leave on all the time. Not knowing which tech (Purifi or GaN) is in my best interest. Both types are available new for around $1,000 for the stereo amp. They have plenty of power, and for all I know, they may all sound about the same. The one I am mostly looking at is the Buckeye Purifi 625 stereo amp. I do realize I could just leave the Mac on for the 15 hours daily and replace the tubes yearly for about 1/5 the cost, but don't we all like to try something different once in a while?

@koestner I listen for 15 hours a day with a CANOR AI 2.10 Hybrid Class D and no tube issues at all. Now I am only in my office 2 weeks out of the month but still, preamp tubes are 1) cheap and 2) not as prone to failure as power tubes.

https://www.thesoundadvocate.com/2022/01/canor-ai-2-10-hybrid-integrated-amplifier-evaluated/

Sadly, you won't find a purveyor of GanFET willing to go toe to toe with one of the better D amps I mentioned above.

@ericrhodes1 This statement is false.  This one is too:

I've listened to them and wasn't overly impressed with any aha moments. Their claim to fame only applies to the cheaper D amps from China and the mass produced, sourced amps used for third party purposes.

There might be Chinese made GaNFET amps but I don't know of one. All the Chinese amps I've seen employ chips (often made by TI) which are not GaNFET based (I don't find these amps very pleasing BTW so I think we're in agreement on that point). Your comment about being cheaper is making me wonder if you know what GaNFETs are. 

This bit is true:

Bruno Putzeys has a good interview where he effectively explains his (Eigentakt) way of getting around GanFet's claim to fame of faster switching speed.

The main advantage of GaNFET is due to their lack of leads on the actual devices (they have solder pads instead) they have lower inductance, which is critical in the output section of the amp. So its much easier for the designer to control stray inductances on the board (inductances can be parasitic and so can oscillate). A couple of minor advantages are lower idle currents (due to lower on resistances of the devices) and less heat (on the same account). Its nice to have an amp that is cold to the touch no matter how long you run it.  Their speed isn't such an advantage since the faster you switch the more RFI issues you can have and you don't need to switch over 500KHz to make a low distortion amp. 

The result is you can have a lot less switching noise interfering with other components in the system. Bruno of course recognizes this and has mentioned it as well. It is a testament to his skills that his circuits rival the noise floors of the better GaNFET amps out there. 

So there are GaNFET amps out there who radiate less noise than a good number of tube amplifiers, which is to say they are very quiet.