Someone on another thread mentioned using a 75 ohm P to S adaptor on the REOs to reduce hiss from the Amp3. So I thought I would try it on my REOs coming out of my Predator.
It softens the high end a little which can be very nice on overly bright recordings, and it really brings out the bass. Overall I think it makes the REOs a little more well-rounded, warmer and smoother. Part of the effect may be that with a little less high-end, I can turn the music up a little higher and therefore hear more midrange and bass, but I also think it does give a very natural sounding boost to the bass. Also with the resistor in place, I use the higher gain setting on the Predator which may be affecting the sound also, although I do balance for fairly equal levels when directly comparing the sound with and without the adaptor.
There is less hiss also, although that was never a problem for me at normal sound levels. However there may be a very slight sense of a blacker background and cleaner transients with the plug in place, but it is hard to say for sure.
And using the little adaptor plug with the built-in 75 ohm resistor means I can quickly switch back if I want a slightly different sound just for a change of pace. All in all a great little tweak to the REOs.The one thing I was not thrilled about with these phones was the bass which not only sounded light but also not quite as natural as the rest of the spectrum, and this helps with that.
I got my adaptor on ebay for $18 here:
ETYMOTIC ER4P TO ER4S RESISTOR ADAPTOR (3.5MM PLUG) - eBay (item 290339218619 end time Nov-09-09 18:53:01 PST)