HA INFO mini-ear Headphone Amplifier
- 6.35mm headphone socket for 16-600Ω Hi-Fi headphones
- Power output: 1000MW ( 32 ohms ), 300MW ( 120 Ω), 150MW ( 250 ohms )
SMSL sApII TPA6120A2 Headphone Amplifier
• Output power: 150mw / 250Ω, 300mW / 120Ω, 1000mw / 32Ω
They use the same opamp as Fiio E9 and some Asus mid-fi sound cards. Both seem quite powerful to run even 600Ω headphones. They are half the price of a new Fiio E9, just wondering where did they cut corners to get the price this low?
There's also one (small) review of the S.M.S.L amp here on head-fi: http://www.head-fi.org/products/smsl-sapii-tpa6120a2-big-power-high-fidelity-stereo-headphone-amplifier-golden/reviews