Mark, as you know, I think the KRC-HR is a better preamp overall and I have no skin in the game as I owned both and have heard them in several different systems. The KBL was a beast for sure, the low output impedance is a direct result of the output topology. It has many transistors in the output stage and was designed to drive long cables... no part was missing. The KRC also has a low output impedance but a very different topology than the KBL, the KRC was one of the first discrete differential designs with discrete phase splitters and phase combiners, overall a very sophisticated design. You could go single ended in and be balanced out and reverse which was cool in the day. The output still designed to drive long cables but the emphasis was the differential output stage. Dan designed this with all he had learned from the earlier designs, so theoretically there should be a sonic improvement, but of course this does not always occur. Power supply was definitely , more amp like in the KBL but the KRC supply is no slouch. Also there are continually new devices that become available and sometimes they can make it much easier to design what you want. I think you have narrowed it down the right way, not rushing to judgment and listening over long periods of time. You should enjoy it for quite some time, of course as mentioned by many there are other options out there. I think there is a beautiful synergy with a really good tube pre and your amp as an option. There are also some really good preamps on the market from many different companies ie.. Ayre, ARC, CJ, Pass, Mcintosh, etc, etc, etc ... to name a few. It is always hard to know when to stop looking for system improvements, it is a part of the quest for sure but there is always something you like better if you keep looking and want to spend the money~ Have Fun!
