SEX 3.0 w/ C4S impedance for HD650 & LCD-2C?

[lyons238]

So on the setup I have the LCD-2C seem to be slightly more efficient than the HD650 but take power well.

So having said that if you had both of these headphones HD650 and an LCD-2 variant. Would you wire up at 4 ohms or 8 ohms? I'm thinking 4 ohms would get me by but might get up into the upper end of the output on the pot with the HD650's, potentially increasing the THD. While on the LCD-2 the 4 ohm option might be good. On the other hand I think the 8 ohm option will be great for the HD650 but potentially give me not much usable range on the LCD-2C. Can someone with some experience with both headphones give me a heads up please?

The goal is to give me the most useable volume range between both headphones, while keeping the noise floor and distortion as low as possible, but at the same time allowing enough power to power both headphones past the point of my normal listening levels, which can be quite loud at some times but a little headroom is always good.

FYI - I listen at normal to what some might consider fairly loud listening levels, especially a few beers deep. I have a JDS Labs EL DAC and EL Amp and on the HD650's I listen at 8-2 o'clock 8-9 being my normal, 12-2 o'clock being my max. On the LCD-2C I listen at 7-12 o'clock, 7-8 being normal, and 10-12 being my max. I plan to use the EL DAC with the SEX 3.0.

Thanks!

[Paul Birkeland]

So having said that if you had both of these headphones or an LCD-2 variant. Would you wire up at 4 ohms or 8 ohms?

4 ohms.

but might get up into the upper end of the output on the pot, potentially increasing the THD.

The position of the pot in conjunction with the load presented to the amp and the output level of the source all determine whether you will actually clip the amp.   

FYI - I listen at normal to what some might consider fairly loud listening levels, especially a few beers deep. I have a JDS Labs EL DAC and EL Amp and on the HD650's I listen at 9-2 o'clock 9 being my normal, 2 o'clock being my max. On the LCD-2C I listen at 8-12 o'clock. I plan to use the EL DAC with the SEX 3.0.

Everything you've said up here would change dramatically if you changed sources (going from the headphone jack on your cell phone to a high end CD player from 1999, for example).  The position of the volume control on an amplifier is exceptionally arbitrary without having all of the other associated information.

Ultimately it is a pretty simple task to rewire the output transformers if you want to try different settings. 

[Tom-s]

For a friend with an LCD-3 and Sex 2.1 i rewired from 8 ohm to 4 ohm. While he liked the increase in details/lushness, there was some bass missing for him. Try both. See what you like best.

[lyons238]

My source will always be the JDS Labs EL DAC via USB to my MacBook Pro. I’ll try 4 ohm first like you all said and then move to 8 I was just curious if anyone had experience and it was an easy choice.