Have a pair of Koss HV/1A that have seen better days. Looking for info and help please on the Koss HV and related Realistic line also. These are the TEN models I have seen in the HV line: HV/1 HV/1A HV/1APlus HV/2A HV/X HV/XS HV1/LC HV/XLC Realistic LV-10 Realistic Pro-60 Are there any other Koss HV or related Realistic models ? I enjoy the sound of the HV/1A. What are the sonic differences between these and the other listed models ? The HV may use a Mylar transducer rather than a cone driver - can anyone give detail about the transducer used in the HV line ? Are the Realistic models equal to their Koss counter-partners ? Same 1st quality or were they B-stock, 2nd quality given from Koss to Realistic ? And, which Koss models corresponds to the 2 Realistic models exactly ? Have seen many HV/1 and HV/1A on used market; were all the various X-types, 1APlus and 2A-type less common or more pricey ? What is the difference between all the models and types, please ? Is the only enhancement in the -LC types the addition of the level control pots, or are there other features ? Specs on any/all models greatly appreciated also. Love the sound of the HV/1A...are other models really close in sound or are some models vastly different and how ? (ex: bass response, etc). Have heard Grado developed the SR line from the Koss HV line, not sure if true, any info ? Thanks for helping.