[mrtwobits]

My first post here...

I currently own a pair of slightly modified Grado SR80i cans and an iFi iDSD Nano USB DAC/amplifier. I really enjoy the sound and have enough gain 99% of the time. I'm interested in getting a pair of HiFiMAN HE-400 cans but I'm not sure about the pairing with the iFi amp. I'm wondering if you guys think I'll have enough volume. I'll post some specs and then ask you guys for your opinion.

Manufacturer's specs:

Grado SR80i
Sensitivity - 98dB
Impedance - 32 ohms

iFi iDSD Nano
Output power - 130mW
Output voltage - 1.65V (>100ohms)
Output impedance - <1 ohm

--------------------------------------------------------------

Measurements from "another" site:

Grado SR60i
Volts required to reach 90dB SPL - 0.088 Vrms
Impedance @1kHz - 33 ohms
Power needed for 90dB SPL - 0.24 mW

HiFiMAN HE-400
Volts required to reach 90dB SPL - 0.129 Vrms
Impedance @1kHz - 51 ohms
Power needed for 90dB SPL - 0.33 mW

Thanks for your help.

 

[Head Injury]

My first post here...

I currently own a pair of slightly modified Grado SR80i cans and an iFi iDSD Nano USB DAC/amplifier. I really enjoy the sound and have enough gain 99% of the time. I'm interested in getting a pair of HiFiMAN HE-400 cans but I'm not sure about the pairing with the iFi amp. I'm wondering if you guys think I'll have enough volume. I'll post some specs and then ask you guys for your opinion.

Manufacturer's specs:

Grado SR80i
Sensitivity - 98dB
Impedance - 32 ohms

iFi iDSD Nano
Output power - 130mW
Output voltage - 1.65V (>100ohms)
Output impedance - <1 ohm

---

Measurements from "another" site:

Grado SR60i
Volts required to reach 90dB SPL - 0.088 Vrms
Impedance @1kHz - 33 ohms
Power needed for 90dB SPL - 0.24 mW

HiFiMAN HE-400
Volts required to reach 90dB SPL - 0.129 Vrms
Impedance @1kHz - 51 ohms
Power needed for 90dB SPL - 0.33 mW

Thanks for your help.

The impedance that output power was measured at is very important, because impedance directly affects the power (i.e., halve the impedance and you get twice the power, all else being equal).
 
The iFi looks to have been measured at 16 ohms. You'll have to divide that 130 mW by about 3 to get the amount of power into the HE-400, so about 40 mW. That's enough to get you around 111 dB of volume by the measurements you posted. IMO that's plenty, but you might have loud listening habits. Your Grado can get to about 114 dB right now. If your player has a digital volume control that gives values in decibels (like foobar2000 for example), try lowering it by 3 decibels and see if your amp still has enough headroom to comfortably hit your normal listening volume. If it does, you're set!
 
You might get slightly more volume than this, as the math tells me the iFi might be current limited at that impedance (about 90 mA max), which isn't an issue with your headphones.
 
BTW if those measurements are from InnerFidelity, you can post or link them without trouble. As far as I know, Tyll is still cool with the mods here.

 

[mrtwobits]

Thanks Head Injury,

That was a helpful and awesome response...and yes, those measurements were from InnerFidelity.

I don't think I listen too loudly. (I might get a little carried away, sometimes.) I'm usually around the 3 o'clock position on the volume control. I think it's mostly turned up with older music that has a little dynamic range and isn't crammed right against the maximum level.