Competitive class D amp suggestions

​I used the LSA GaN Voyager  in my main system for a few days. Not surprisingly, it didn't sound worse in the main system, which is a good characteristic. At the same time, the main system revealed some technical problems related to the amp. I noted this before in my second system as well but I suggested that the problem could have been in the preamp. 

First, the amp just does not sound well  with the balanced inputs - there is a quite notable lack of the middle and high frequencies with the balanced inputs ( i tried two different quality  balanced cables). Fortunately, one of the RCA inputs has no such problem. 

Second, a quite strange thing happens. With both XLR inputs, the left channel is too weak.  And with both RCA inputs the right channel is too weak. I mean, even if i stand in front of the speaker, the sound coming from the other speaker is dominant. The preamp in my second system has the balance control, so this issue was somehow "settled" by reducing the volume in the normally sounding channel by about 40%. The T&A DAC/preamp in my main system has no balance control, so it was just impossible to use the amp with either XLR or RCA inputs. ​Then i used the rear switches to put the right channel in XLR and the left channel with RCA modes . This was the only way to achieve a more or less balanced sound. 

Third, i think the amp has some phasing problem. Apparently, it is made out of phase. But when I swapped the positive and negative speaker outputs, the amp remained out of phase. Perhaps, this is not a big problem but something may also be wrong with this. 

Based on my small experience with the combined XLR-RCA auditioning in my main system (thanks to the rear amp switches that permitted me to use such an option), i think there is nothing particular to complain about  the sound quality of the amp (judging analytically). At the same time, there is no point in comparing it with my SET tube amp that just sounds more real, full and alive. This can be subjective. But perhaps, not. Just take one of the CDs I used to compare the SQ of the two amps. It is Keith Jarrett's "Buy buy blackbird" (hey @jjss49 !). It is a particularly well recorded CD. Although it is a studio album, one can feel the studio environment and the musicians on each of the instruments, just as if it were a live recording. The SET amp gives this feeling, the Voyager does not (so far as it is  now). 

Perhaps, the Voyager may still improve (it should have about 110 hours of burn-in). I will be able to judge once I get it back from Underwood Hi FI. I am going to ship it for repair today. 

@niodari 

Here's the measurement of the Technics SU-G700M2, which may not be exactly a class D amp, or a GaNFet amp, but which is something close.

As you'll see, some of the higher order harmonics are higher than one often sees, and normally you only want to see the second and third harmonics around that level.  John Atkinson commented:

"The fifth harmonic in both channels, the seventh harmonic in the left channel (blue trace), and the ninth harmonic in the right channel (red trace) were almost as high in level as the second and third harmonics. Although these harmonics are low in level, lying between –80dB (0.01%) and –70dB (0.03%), they could be audible at high listening levels in the region where the ear is most sensitive."

@twoleftears , I wonder how this integrated amp sounds with this speaker impedance correction feature. E.g., the distortion at higher order harmonics (the pick at 1k and the following ones at 2k etc) is considerably higher than that of the first, 2nd and  3rd order harmonics, they should be audible. Given that, it is really interesting how this is reflected on the SQ. 

The diagram is  "unusual" also because it shows  a big difference between the two channels where a little distortion is observed in the blue channel as there are only two blue picks.

For the Atma-sphere class D amp: Is a preamplifier necessary if only connecting a streamer/DAC to it? The streamer/DAC has it’s own volume control (if I want to enable it). Lumin S1.

Someone I came across (Ocean) mentioned this class D amp is definitely worth checking out.

Also, which preamplifiers are recommended for it (that have a remote)?

Other than heat and efficiency, what do you think are the pros/cons of moving to this amplifier from an 805 tube amp (Line Magnetic LM-805ia)?

@veerossi The designer of the Atma-Sphere GaN amp @atmasphere is on here regularly and hopefully he’ll chime in here with some very helpful suggestions and insights.  I believe he now uses his new GaN amp in his own system even over his very highly-regarded OTL tube amps so that may give you a clue, but hopefully Ralph can add more meat on the bones here for you.