Reading specs (headphone outs)

[zeekat]

Looks like there's no standard in supplying interface specs by manufacturers, me having no electronics knowledge whatsoever doesn't help.

So I have headphones with 32 ohms impedance and 112dB/mW sensitivity. They're nice and loud with Mackie interface, which has headphone out described as "max level 8mW into 600 ohms". They sound pretty weak even maxed out on Tascam, which has "18mW per channel into 32 ohms".

Sapphire 2i2 has headphone out described as 10 ohms, max level +10dBu. Can I guess from this how well would it work with phones like mine?

There should be some unified form of specs so us ignoramuses could easily compare devices.