Manley Chinook SE MK2

@pindac  the Chinook came with Tungsram as these were the choice of tubes by Upscale. I believe this is why it was named the SE MK2. Now it comes with EH I think because NOS is getting scarce.  

@tablejockey thank you for the information 😁.  PL offers great value. 

There are two tubes that would make a difference so far as "matching" goes. Those are the tubes that provide gain in the L and R channels, respectively. In the Steelhead these provide the "top half" of a cascode where the bottom half is probably an FET. The other two tubes are used to create an output stage that is very low in output impedance; in effect they form an unusual type of cathode follower (a stage that turns voltage into current). There is no added gain in the output stage, so the sound of tubes in a cathode follower is generally thought of as not a prominent factor in the overall presentation. I think tube matching is overrated, because tubes are aging as we use them, and no two tubes will age in exactly the same way or rate. So what "matches" today may not match tomorrow. And yet, I am guilty of perceiving that some tubes of any type sound better than other tubes of the same type. In my Steelhead, I use Siemens CCa, I think. I would not shed a tear, however, if some day I had to use some other brand.

By the way, as regards the autoformers in the Steelhead, I get the feeling that my Steelhead sounds best through its MM outputs, where there is no autoformer in the signal path. Interestingly, in the Steelhead, I have read (never tried it) that you can get up to the max 65db of phono gain via the MM outputs.  To me that suggests the autoformers are more for impedance matching to MC cartridges than for their potential to step up voltage.  Also, if you look inside, you can see that for each input R setting available via the rotary switch, there are discrete pairs of resistors whose values match the choices offered via the rotary switch. (If the autoformers were used like SUTs, you would think that the different input impedances would be mostly the product of what pair of primaries is selected.)  It's a bit of a mystery to me.  Manley are very secretive and certainly will not provide a schematic; I have asked.

By the way, as regards the autoformers in the Steelhead, I get the feeling that my Steelhead sounds best through its MM outputs, where there is no autoformer in the signal path. Interestingly, in the Steelhead, I have read (never tried it) that you can get up to the max 65db of phono gain via the MM outputs.  

This has been widely reported-that the MM input with MC often sounds best-by various reviewer and owners. I have tried it and agree. 

I did replace some of the putative MC load resistors in my Steelhead with TX2575 resistor equivalents. (TX2575 are the best most transparent phono load resistors I have ever heard and by general consensus.) That may have improved SQ in the MC circuits; I would not swear by it.