Quote:   One that has come up in discussions is the Alesis RA150.   It's a SS fully balanced power amp.   4 ohms: 75 watts RMS per channel 8 ohms:  45 watts RMS per channel 8 ohms:  150 watts RMS, bridged mode        THD 0.02% @ 4ohms, 20Hz - 20kHz    ...

Quote:   Wow - that's amazing.   I think I'd need to buy a new suit...and put it on... just to visit their web site.

Quote:   That didn't dismay me by itself.   But you have to add in a project box (pre-punched, of course), the input and output connectors, and a soldering station.   It isn't so much the cost of the items...it's all the time doing research and hunting things down.

I see. They rate it at a max input of just 20 VRMS.

Ok, thanks.   Still one (or a pair, actually) could be used to attenuate the output signal from a speaker amplifier to a set of headphones, as long as they were oriented correctly (and if they were able to connect to some sort of modified headphone cable).  

Quote:   Do you know if these attenuator adapters are directional ?   In other words, are they constructed to work only with a signal moving in one direction ?   If that were the case, for example, then it would make a difference if it was attached at an output source as opposed...

Quote:   I think that the quality of a resistor in series may actually be more important than the resistors in parallel.   The audio signal has to travel through the in-series resistor.   Induction would probably change the sound quality. It my not introduce distortion (noise) but...

Quote:   What if a single parallel resistor (for one channel only) were to fault. I'm thinking of the HE adapter box configuration. In that case the entire circuit wouldn't be broken.   Would that result in the corresponding side of the headphone (the right or the left) becoming louder ?

Thank you for the follow up. I'm definitely going down this route.

Quote: How did the volume control attenuation compare in these configurations with the different HP's ?   I'm wondering if there was considerably more play (an ability to fine tune between soft and loud ) with the 5-LE and is that somewhat restricted on the set-up you have for the...

Quote:   That review is there...under the HE500   http://www.amazon.com/HiFiMan-HE-500-Headphones/product-reviews/B005DL2JCI/ref=cm_cr_pr_hist_5?ie=UTF8&filterBy=addFiveStar&showViewpoints=0