Good RS1 setup. I don't own a ME+, but have heard those several times over the years with my RS1 at local meets. Grados in general respond VERY WELL to output transformer coupling, and its the hammond 12 watt 119DA OTs in the ME+ that makes it unique. AFIAK maple tree is the only HP amp maker in existence that uses these OTs. A while ago there was a schematic floating around the www. According to the manual, the right and left tubes are positioned as such in the chassis... R is on the right L is on the left as you face the front. http://hollowstate.netfirms.com/manuals/Eplus%20HD%20users%20manual.pdf Ear+ -VS- D100... use your ears as a guide. Plug it into whichever sounds best. I have always found my RS1 (and HF1 & SR60 for that matter) to be my least amp-sensitive phones in my mid-fi collection. I think it has to do with their sensitivity/efficiency. That combined with the Grado harmonic distortions + resonances that saturate and color everything from the upfront signal chain. Cool thing about the Ear+ is they make use of both secondary coils on the Hammond OTs. So don't hesitate for a second to plug the Grado into the 300 ohm jack. Note also that new tubes (as opposed to used) have a certain burn-in time, sometimes they just need hours of use to settle down, and the result is an amp circuit that goes through changes as the tubes burn. My response to #3 is harmonic distortion can be a good/bad thing, depending on the individual preference. Thats the beauty of tube rolling (and OP amp rolling too), go with what sounds best to your ears. GE and Sylvania are generally regarded as work horse tubes. They cranked those things out by the millions and can be found NOS, used...etc. Mullard, Amperex, Telefunken, RCA are other generally highly regarded brands. Italicized that because there was also the world of tube re-branding. So many tubes screen-labeled as brandA, were in reality manufactured by brand-B. Get to know your tubes by construction as well as brands... ID your plates, getters, pins, bottles...etc, and Happy hunting for that magic tube!! Theres almost always a headfi tube rolling thread dedicated to the most popular amps and tubes... start with that to get a consensus. Keep in mind too though that they are just subjective preferences/impressions. For your #4, I think you've got a great all around single ended setup. You've only just scratched the surface with the RS1, its a good headphone but not without its limitations. The Ear+ can accommodate a wide range of impedances too. I have always believed the headphone is THE MOST critical component in the chain, and has the biggest influence on what the system will sound like.... see where I'm going with this? Without a doubt... get yourself some other headphones to try out in your rig. Despite being a ~$600 headphone, and a long standing favorite of mine, frankly there are other cans out there that blow it away in certain aspects, with certain types of music... at a fraction of the RS1 price.