Setting the phono cartridge loading and gain on the Audio Research SP-9 MkII is a bit extreme, even for me.
The two beige resistors and the two silver/red capacitors shown in the photo above set the cartridge loading and need to be removed and different ones soldered into their place to change it. If you look up how to read resistor values you will see from the colour bands that these resistors are 47 kilohms.
And how do you modify the gain?…
See the extra lumpy solder bridging from “A” on the main circuit board to the other trace?… Desolder that. Luckily it comes shipped for high gain which is what I want for the Denon 103R LOMC (low output moving coil) phono cartridge anyway.
Acoustic Research explains this as resulting in better sound quality, which is certainly true in theory (less circuitry in the form of switches = better sound). But I’ll take the convenience of having some switches on the front over any very marginal gains in sound quality since what ultimately happens is that it’s such a PITA to change cartridge loading that very few do it and run their phono stage incorrectly instead (which would in theory be a far greater sonic penalty).
Having said that, Ive been running the ARC SP-9 MkII as it ships from the factory with 47k cartridge loading and unmodified gain with good success, even when I dropped in the Denon 103R. The SP-9 MkII is probably one of the few preamps that doesn’t say “MC” on it and yet has enough gain for the 103R.
The Threshold FET 9 in the photo above is a piece of cake by comparison, although the previous owner had never opened it up. It has dip switches for impedance and capacitance loading and jumpers for gain. Of course, you still need to know how you want to load your cartridge, but at least it’s easy to accomplish once you do.