[ashutosh17]

Hi everyone

I just got the Massdrop O2s for my HE4xx from eBay. There's nothing on the amp itself that suggests if it's the Standard Gain (2.5x Low, 6.5x High) or Medium Gain (1.0x Low, 3.3x High) version. Is there a way to know that from the Amp itself?

Also is the medium gain version (1.0x Low, 3.3x High) enough to drive the HE4xx? Or do I need the standard gain version?

 

[tomb]

It appears to me that looking up all versions of the Massdrop O2 included a gain switch. Try the switch in different positions and see what you like best.

Just an FYI, but gain is not power. What you want is a gain that allows you to adjust the volume most conveniently. High gain with highly efficient headphones will have you adjusting the volume in the first quarter turn of the knob. Conversely, low gain with low efficiency headphones will have you adjusting the volume in the last quarter turn of the knob. Unfortunately, volume pots tend to have their worst channel matching at the extremes of travel, both low and high. You want a gain with your headphones that allows you to adjust the volume levels you prefer around the mid-range of the pot.

All of that is only tangentially related to power, because regardless of gain or volume pot impedance, near zero at the volume knob travel is approaching maximum resistance, while near the end of the volume knob travel, resistance is approaching zero.