Pani, As you may know, the last and still latest Klyne models go up to "7". The "6" series is second tier in terms of cost, with the 7 series at the top. There are some variations in this theme; I once knew for sure what is the difference between the 6 and the 7 that confers the higher price on the latter, because externally they look identical. I think it was provision for balanced output and the use of an outboard power supply in the 7, which mainly allowed for a beefier power transformer and more filter capacitance. Further, there was and maybe still is ongoing evolution in the phono section, for both the 6 and the 7 series. Further, further, there are two subtypes within the 6 series, 6LE and 6LX. The LX series has an outboard PS, identical to that of the 7 series. So a 6LX is pretty much the same as a single-ended version of the 7 series, assuming all 7s have balanced option. I own a 6LX for which I built my own outboard supply; I got it at a low price, because the PS was missing entirely. I then sent it back to Stan Klyne for work on the phono section. I think he can install the very latest 7 series phono circuit into a 6 series, or at least the 6LX. I opted for second best, because of the cost differential. My point is that not all these Klyne preamplifiers are created equal. My only regret with my 6LX is that I did not opt for the max phono circuit; I may yet send it back to Stan for that. He was very helpful to me when I was building the outboard PS, as well. A very nice guy. Thus, I recommend you find out what phono stage is built into the 6 that you are contemplating; the sonics will vary depending upon the answer to that question. Stan may be able to help you figure out what version you have there, if you supply him with the serial number.
Bottom line: I do believe that a max'd out 6 or 7 series is in the same league with the other units you mention or maybe better, but like ebm says, only you can be the judge of that.
Bottom line: I do believe that a max'd out 6 or 7 series is in the same league with the other units you mention or maybe better, but like ebm says, only you can be the judge of that.