I got so many requests to describe it, and it takes up so much space, that I have a saved paragraph on the subject. If you PM me, I will send it to you. I don’t wanna bore everyone else. It really amounts to upgrading the coupling capacitors, to both improve on the quality of the stock parts and also use a value that makes sense based on what the stage has to drive (Manley uses a very unnecessarily large capacitor value), and also just removing a 47R resistor from the signal path.
What the heck: here is the paragraph.....
"I could not get a schematic; Manley does not provide a schematic even for professional repair shops. But if you read an interview with Evanna Manley, several years ago in 6 Moons, she describes the output stage. I won't reiterate her summary (please google it; look for the Steelhead review in 6Moons) but suffice to say that the output of the phono stage, which either drives the volume control if you use it as a full preamplifier or the outboard linestage, if you use it as a phono stage only, uses a 47-ohm resistor in series with the signal followed by a 30uF output coupling capacitor, which in my opinion is mediocre in quality, at best. This capacitor and what follows are holding back the performance of the Steelhead, IMO. I removed the 47-ohm resistor entirely; it's not needed for anything, and I replaced the 30uF coupling cap with a much higher quality 10uF capacitor. (Choose whatever you like but spend the $$$ for a very good one.) You need 10uF, I guesstimate, because the volume control seems to have a 5K ohm input impedance (very low). (10uF driving a 5K ohm load will give you a very low bass cut-off; 30uF is way overkill.) If used as a full function preamplifier, the output capacitor drives the attenuator as noted, and the attenuator drives the linestage. The linestage itself is nothing but a White cathode follower; it adds no gain to the signal from the phono section, but it provides a very low impedance output to drive any amplifier. The output from the linestage section (after its White cathode follower) uses yet another 47 ohm resistor in series with yet another 30uF capacitor of the same type and brand. That connects to the linestage output jacks. I removed that 47R resistor and replaced THAT capacitor with a 4uF film cap that I like very much. Since my amplifier has a 50K input impedance, 4uF is more than adequate to get good bass. Those two coupling capacitors, from phono stage output to attenuator and from attenuator to linestage output have everything to do with the SQ of the Steelhead. There is a lot of room inside the chassis to use just about any film capacitor you might want, but I would recommend the 10uF Dynamicap E (for “Electronic”) for the output of the phono section that drives the attenuator, and for example a 4uF Dynamicap E for the output of the linestage. Dynamicaps can be purchased from Michael Percy. Other choices are up to you."
PS. I don't know if the Chinook output stages (from phono to linestage, then from linestage to output) are identical to that of the Steelhead or even if the Chinook has a linestage.
