Just trying to qualify my comments about the original usually being the best. I bought a very expensive boxed set of classical music ( I dare not mention the composer ) many years ago. A new digitally enhanced upgrade came out. - It was not a patch on the original. Never play it, always the original Georg Solti version from the 60's.
How do you improve on perfection? Or is that a silly question? They got it right first time with the ISF model range ( once they got the diff sorted ). The later models - RCF, GSF, are great and I would have one any day but the original has a certain cachet or quality that makes it special, or maybe just me being biased?