Do audio output voltage/power level benchmarks exist?

[avaya00]

My HTC Evo 3d can't power the factory receiver in my car (and it's not a deluxe/impressive stereo system). My car sound quality has been:
1. CD (10 out of 10)
2. FM Radio (9 out of 10)
3. Bluetooth from phone (4 out of 10... is there any way to disable whatever crappy compression it has?)
4. Line out from phone (2 out of 10, no highs and blatted/quiet lows due to underpower)

My Evo can drive ~100 ohm Sennheiser HD 435 (under $100 headphones) but can't drive a pair of 300 ohm headphones that I have. My friends iphone4 has no problems driving the 300 ohm headphones or my car receiver. Anyone know if these types of stats exist anywhere? I don't want to switch to Apple.

 

[Kevin OQuinn]

When you say "drive" what exactly do you mean? Plugging in to the headphone jack should work just fine, since the headunit shouldn't really be giving it any type of high load.

Is the volume noticeably lower than everything else that gets plugged in?

What kind of headunit is it?

 

[avaya00]

Volume is not noticeably lower, just the highs and lows are flatted on high resistance devises. I agree the line-in to my car doesn't make any sense, maybe it's a problem with the cord.

The headphones are very old Sennheiser's and just list 300 ohm impedance

 

[_Zguy__]

My advice is get a headphone amp, bout 30 dollars lighter sized box and should greatly improve sound quality

 

[Kevin OQuinn]

My advice is get a headphone amp, bout 30 dollars lighter sized box and should greatly improve sound quality

These are typically driven by the USB port, will those even work with a phone?

 

[EatMyTracers]

I use a Fiio E6 amp and it seems to help a lot with certain phones.
http://www.amazon.com/Fiio-E6-Headp...ag=hawk-future-20&ascsubtag=UUacUvbUpU2001884