What matters is what has the best synergy and sounds best to you.
A word of caution though…there are times when our brain perceives different as better. Taking time, and it could be hours, days or weeks, to let it all settle and finalize your assessment is critical.
As a side note, I had the original LS-25 and loved how it sounded. Not familiar with the MkII version…
surprising comparison of tube preamps
Hi and thanks for your help. I have been using an ARC LS25 II preamp going into a Mcintosh Mc462 amp. One source is a turntable going into a Parasound JC3+ phono pre. When the ARC broke, I tried a Bottlehead Crack headphone amp as a preamp. I was very surprised to see how beautifully this worked. Really rich sound. Maybe it was less accurate (could not do a direct comparison with the LS25), but it was certainly great to listen to, for my taste. I looked into this some and wondered if the lush sound came from the fact that the Bottlehead was using a simple SET OTL circuit, compared to the hybrid circuit in the LS 25. Still you would think that the ARC unit, costing so much more, would sound better. I am wondering if people have an explanation for this but, more importantly, have been looking into getting a very simple tube pre to use for the phono part of the system. Mapletree audio sells a simple preamp that I believe is a SET OTL (are all preamps OTL?). Al Freundorfer, the designer and owner, kindly agreed to make me a modified version to test. Some circuits, including a buffer he sells, have the ability to adjust the 'warmth' and extent of tube sound - he would build this into his amp for me (it is available on some of his other products). Is this a good idea? Could I reproduce the effect I heard with the Bottlehead? Not sure how those 'warmth adjusters' work. Thanks a lot for your help.