The better perceived clarity or dynamics could be caused by clipping, this is how loudness war mastering works. When people get used to hear such kinds of sounds, the non-clipping version could indeed sound worse to some people due to subjective preference.
A lot of studio interfaces can deliver more than 4Vrms without clipping so it is not necessary to limit yourself to the MQA models. If you already own more than one MQA DACs, I don't see why you cannot get a non-MQA one with higher non-clipping output for non-MQA content, unless you almost listen to MQA exclusively.
About that: "The better perceived clarity or dynamics could be caused by clipping." I must admit that this is the first time I have heard of such a thing. But the fact is that by gradually turning down the volume on the DAC I find a point where the clipping stops. Of course, the limit is not the same for all songs, but you can find a value that is ok for almost all of them. This would mean that the music is listened to at the limit of clipping. Of course, the closer the value is to -0dB, clarity and dynamics are better. But believe me the sound is incomparably better than with a filter or any other manipulation. Some albums, and there are quite a lot, can be listened to at -0dB, an incredible sense of clarity and power of voice, piano, saxophone, guitar..... If it is due to clipping or pre-clipping, thank them for that. Of course, everything depends primarily on the quality of the recording.
I love detailed and analytical sound, fast clear bass. That should be taken into account, because some people might not like it. Let's say the sound is similar to open studio headphones, as opposed to the sound of closed headphones with full bass and not so clear mid and upper spectrum.
By the way, these are the complete specifications of the SMSL D400ES
Input: USB/Optical/Coaxial/Bluetooth/IIS/AES
Output: RCA/XLR
Line output amplitude:
XLR 5.2Vrms
RCA 2.5Vrms
THD+N: 0.00005%(-125dB)(UN-WTD)
Dynamic range: 133dB(XLR),128dB(RCA)
SNR: 133dB(XLR),127dB(RCA)
USB transmission: USB 2.0 Asynchronization
USB compatibility:
Windows 7/8/8.1/10(Needs Driver)
Mac OSX10.6 or Later, Linux(Driverless)
MQA decoder: USB/Optical/Coaxial/AES
MQA-CD decoder: Optical/Coaxial/AES
Sampling rate & Bit Width:
USB PCM 44.1~768kHz(32bit)
DSD 2.8224~22.5792MHz(1bit)
Optical/Coaxial 44.1~192kHz(24bit)
DoP DoP256(USB),DoP64(Optical/Coaxial)
Bluetooth 5.0
LDAC: 24bit/96kHz (990kbps/660kbps/330kbps)
aptX-HD: 24bit/48kHz_576kbps
aptX: 16bit/44.1kHz_352kbps
SBC: 16bit/44.1kHz_328kbps
AAC: 16bit/44.1kHz_320kbps
Power Consumption: < 10W
Standby power: <0.5W
Size: 240x188x43mm (WxHxD)
Weight: 1.8kg/3.97Ib