Ah yes type-o.
Still, the modi and the a100 will not get near the compass 2. The compass has a better dac and nearly 3 times the power of the a100.
Let's evaluate some things here:
First is the power requirements for the HE-500, courtesy of
this thread
Manufacturer | Model | S@1V [dB SPL] | Z [Ω] | Voltage [V] | Current [mA] | Power [mW] | Gain [dB] | Notes |
| | | | | | | | |
Hifiman | HE-500 | 102 | 34 | 2.512 | 73.879 | 185.576 | 2 | |
| | | | | | | | |
The output power to reach 102dB SPL (very loud) is only 185.576mW for HE-500. Both amps have way more than enough headroom.
Compass 2:
Output level: Headphone output : 11V RMS
Output Power: 2000mW / 50 ohm
Yulong A100:
Output level: Headphone output: VPP:20V
Output Power: 343mW / 50 ohm
S/N Ratios:
are similar between the two, but i would speculate that the Compass 2 is worse because the DAC is built-in with amp, which is never good, and it doesn't state if it's with both DAC/Amp or either.
THD+N:
Yulong A100: 1KHZ, <=0.0007%
Compass 2: Not specified, again not a good sign.
In general, the A100 uses a higher quality power supply, transistors and OP amps.
Modi AKM4396 vs. Compass Dual wm8741:
Modi:
Analog Summing, Active Filtering: Based on AD8616 with precision thin-film resistors and film caps.
Frequency Response: 20Hz-20KHz, +/-0.1dB
Maximum Output: 1.5V RMS
THD: <0.003%, 20Hz-20KHz, at max output
IMD: <0.004%, CCIR
S/N: >100dB, referenced to 1.5VRMS, unweighted
Crosstalk: -80dB, 20-20kHz
Compass 2:
20Hz - 20KHz (-0.2DB , DAC + amp )
Missing alot of specs...
Summary:
The Compass 2 most likely has the better DAC, but when it's in the same box as the amp, it's compromised. If he decides to upgrade later on, it more convenient to have separates. The compass 2 is more versatile, but why pay for those options if you don't need to? Modi DAC has 5-year warranty. Compass 2 is one year, and you pay shipping overseas. Yulong is one year, shipping reimbursed.
Both are certainly great choices, but the Compass 2 isn't necessarily better, especially since much of the specs are a complete mystery.