[davstev]

It's been awhile since my last post but I know that this is the place to ask...

I have a very nice pair of Grado HP-1000 drivers in custom black walnut cups. I'm using an Accuphase C200 preamp to amplify them. Both of these pieces are excellent, but I wonder how well mated they are. I have to turn the volume up to the 1 o'clock position just to get it to a normal volume. When I want to crank it, it's in the 3 or 4 o'clock position. In other words, there's just not a lot of power, not enough power, coming from the preamp, toward these rather inefficient headphones. However, I can't complain about the sonics, they are lovely. It just bothers me to have to crank it so much just to get a normal volume. There's not much headroom.

I've read from a reliable source that for my Accuphase pre, the voltage supply to the headphone amp is only about 4.5V. I also know that HP-1000's are rated at about 40 ohms.

If I wanted to purchase a new pair of phones that would mate well with this low-output preamp, what ohm value would be ideal? What other specifications matter here? Any recommendations for headphones that would mate well?

Thanks !

 

[Dulalala]

I have to turn the volume up to the 1 o'clock position just to get it to a normal volume. When I want to crank it, it's in the 3 or 4 o'clock position.

Just to be clear, the volume knob goes to 12 o'clock and turns clockwise right? I'm not sure how you got the impression that if it's at 4 o'clock and is loud enough that there isn't enough power.

I've read from a reliable source that for my Accuphase pre, the voltage supply to the headphone amp is only about 4.5V. I also know that HP-1000's are rated at about 40 ohms.

If I wanted to purchase a new pair of phones that would mate well with this low-output preamp, what ohm value would be ideal? What other specifications matter here? Any recommendations for headphones that would mate well?

The impedance of a headphone does not directly correlate to the "drive-ability" of the headphone. The impedance of a headphone is basically just the resistance of the circuit, but since the analog signal for audio is AC, it's impedance.
A lower ohm rating, in general means higher current draw. A higher ohms rating means higher voltage draw. What's more important is that you find out the sensitivity of the headphone along with the impedance to find the total power draw/voltage draw, at a specific frequency, to reach a certain dB SPL and compare that to how much the amplifier maximum output is to see whether the amp can run it or not.