I cannot compare the Vali 2 to the Asgard 2, as I have never heard the Asgard 2, so maybe someone else can chime in on that.
In regards to low Z cans, I can confirm that the Vali 2 does an excellent job with them. All of my 'phones (aside from the HD-650) are also low Z and the Vali 2 has no problems with them.
As noted earlier ITT, when using low Z cans on high gain mode, there is a slight low level hum that can be heard. To my ears, the hum sounds more like an electrical/60 second cycle type of hum, than what I would consider amp noise, if that makes sense.
The hum does not change volume with the amp. It remains at the same low level no matter the volume setting (even completely turned down). I am not sure of the hum in inherent in the tube, amp design, or possibly even something that power conditioning could take care of. Having said that, I didn't even notice the hum until it was mentioned by another user, and I went back to listen for it. It really is a non-issue IMO, especially because it disappears completely when in low gain mode (which you would be using for low Z 'phones anyway) and I cannot hear it at all (with either gain setting) on my 650.
Specs according to the Schiit website are as follows:
Frequency Response: 20Hz-20Khz, -0.2db, 5Hz-150KHz, -3dB
Maximum Power, 16 ohms: 1300mW RMS per channel
Maximum Power, 32 ohms: 1000mW RMS per channel
Maximum Power, 50 ohms: 650mW RMS per channel
Maximum Power, 300 ohms: 270mW RMS per channel
Maximum Power, 600 ohms: 140mW RMS per channel
THD: <0.03%, 20Hz-20KHz, at 1V RMS, low gain
IMD: <0.05%, CCIR, low gain
SNR: >99db, unweighted, referenced to 1V RMS, low gain
Crosstalk: -68dB, 20Hz-20KHz
Output Impedance: 1.2 ohms in low gain mode, 5.8 ohms in high gain mode
Gain: 5 (14dB) or 1.25 (2dB)
Topology: Tube voltage gain with convolved bipolar current mode inverter and discrete bipolar class AB output stage
Protection: delayed start and fast shut-down with muting relay
Power Supply: wall wart with 24VAC and 6VAC outputs, regulated HV and LV rails for tube and bipolar components, 6V AC heater
Power Consumption: 9W
Size: 5 x 3.5 x 2.75”
Weight: 1 lb
Hope that helps!
-Dave
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