The HRD has been sold on ebay. Sorry for potential buyers. As far as what mods jim (Omega mods) does, it seems variable. someone asked on ebay if he did the mid push/pull mod. which he didn't on mine. Most mods are done to the reverb and gain circuits, the cleans sound similar to the stock ones, but definitely different, as well. It seems fairly ambiguous on his website, as well. I know it is a pretty tight sounding amp, and is a tone beast. The gain channels and reverb are definitely a big improvement. I think he is going for a robin ford/santana sound.
like waves against the bandstand dancers broke